diff --git a/col.go b/col.go
index 7b441c5..20dc111 100644
--- a/col.go
+++ b/col.go
@@ -100,7 +100,7 @@ func (rk RK) float() float64 {
 func (rk RK) String(wb *WorkBook) string {
 	i, f, isFloat := rk.number()
 	if isFloat {
-		return strconv.FormatFloat(f, 'f', -1, 64)
+		return strconv.FormatFloat(f, 'f', wb.defaultFloatBit, 64)
 	}
 
 	return strconv.FormatInt(i, 10)
@@ -188,7 +188,7 @@ func (c *NumberCol) String(wb *WorkBook) []string {
 		return []string{v}
 	}
 
-	return []string{strconv.FormatFloat(c.Float, 'f', -1, 64)}
+	return []string{strconv.FormatFloat(c.Float, 'f', wb.defaultFloatBit, 64)}
 }
 
 type FormulaColHeader struct {
@@ -353,7 +353,7 @@ func (c *FormulaCol) parse(wb *WorkBook, ref bool) {
 		} else {
 			c.value, flag = wb.Format(c.Header.IndexXf, c.Header.Value())
 			if !flag {
-				c.value = strconv.FormatFloat(c.Header.Value(), 'f', -1, 64)
+				c.value = strconv.FormatFloat(c.Header.Value(), 'f', wb.defaultFloatBit, 64)
 			}
 		}
 	}
diff --git a/format.go b/format.go
index c0405db..b98ba3a 100644
--- a/format.go
+++ b/format.go
@@ -78,7 +78,7 @@ type Format struct {
 }
 
 // Prepare format meta data
-func (f *Format) Prepare() {
+func (f *Format) Prepare(wb *WorkBook) {
 	var regexColor = regexp.MustCompile("^\\[[a-zA-Z]+\\]")
 	var regexSharp = regexp.MustCompile("^\\d+\\.?\\d?#+")
 	var regexFraction = regexp.MustCompile("#\\,?#*")
@@ -133,11 +133,15 @@ func (f *Format) Prepare() {
 			if f.bts > 0 {
 				f.bts = f.bts - 1
 			}
-		} else if t := strings.Index(f.Raw[0], "General"); -1 != t {
+		} else if -1 != strings.Index(f.Raw[0], "General") || -1 != strings.Index(f.Raw[0], "general") {
 			f.bts = -1
 		} else if t := strings.Index(f.Raw[0], "@"); -1 != t {
 			f.bts = -1
 		}
+
+		if -1 == f.bts {
+			f.bts = wb.defaultFloatBit
+		}
 	}
 }
 
@@ -148,10 +152,6 @@ func (f *Format) String(v float64) string {
 
 	switch f.vType {
 	case TYPE_NUMERIC:
-		if 0 == f.bts && nil != f.Raw && "general" == f.Raw[0] {
-			f.bts = -1
-		}
-
 		ret = strconv.FormatFloat(v, 'f', f.bts, 64)
 	case TYPE_CURRENCY:
 		ret = strconv.FormatFloat(v, 'f', f.bts, 64)
diff --git a/workbook.go b/workbook.go
index cd16607..cb31c8c 100644
--- a/workbook.go
+++ b/workbook.go
@@ -10,31 +10,33 @@ import (
 
 //WorkBook excel work book
 type WorkBook struct {
-	Debug          bool
-	Is5ver         bool
-	Type           uint16
-	Codepage       uint16
-	Xfs            []XF
-	Fonts          []Font
-	Formats        map[uint16]*Format
-	sheets         []*WorkSheet
-	Author         string
-	rs             io.ReadSeeker
-	sst            []string
-	ref            *extSheetRef
-	continue_utf16 uint16
-	continue_rich  uint16
-	continue_apsb  uint32
-	dateMode       uint16
+	Debug           bool
+	Is5ver          bool
+	Type            uint16
+	Codepage        uint16
+	Xfs             []XF
+	Fonts           []Font
+	Formats         map[uint16]*Format
+	sheets          []*WorkSheet
+	Author          string
+	rs              io.ReadSeeker
+	sst             []string
+	ref             *extSheetRef
+	continue_utf16  uint16
+	continue_rich   uint16
+	continue_apsb   uint32
+	dateMode        uint16
+	defaultFloatBit int
 }
 
 //newWorkBookFromOle2 read workbook from ole2 file
 func newWorkBookFromOle2(rs io.ReadSeeker) *WorkBook {
 	var wb = &WorkBook{
-		rs:      rs,
-		ref:     new(extSheetRef),
-		sheets:  make([]*WorkSheet, 0),
-		Formats: make(map[uint16]*Format),
+		rs:              rs,
+		defaultFloatBit: -1,
+		ref:             new(extSheetRef),
+		sheets:          make([]*WorkSheet, 0),
+		Formats:         make(map[uint16]*Format),
 	}
 
 	wb.parse(rs)
@@ -48,6 +50,11 @@ func (w *WorkBook) SetDebug(debug bool) {
 	w.Debug = debug
 }
 
+// SetFloatBit 设置小数默认保留位数，默认值 -1 不限制
+func (w *WorkBook) SetFloatBit(n int) {
+	w.defaultFloatBit = n
+}
+
 func (w *WorkBook) parse(buf io.ReadSeeker) {
 	b := new(bof)
 	bp := new(bof)
@@ -194,7 +201,7 @@ func (w *WorkBook) prepare() {
 		}
 	}
 	for _, v := range w.Formats {
-		v.Prepare()
+		v.Prepare(w)
 	}
 }