diff --git a/text2img/parse_font.go b/text2img/parse_font.go
index f514252..79bd7a4 100644
--- a/text2img/parse_font.go
+++ b/text2img/parse_font.go
@@ -667,7 +667,7 @@ func RenderTextToImage(fontContent *truetype.Font, text string, fontSize float64
 	// 计算总高度（每行高度+行间距）
 	totalHeight := 0
 	for _, height := range lineHeights {
-		totalHeight += height + lineSpacing + 1
+		totalHeight += height + lineSpacing + height/12
 	}
 	// 减去最后一行多加的行间距
 	if len(lineHeights) > 0 {
@@ -679,6 +679,13 @@ func RenderTextToImage(fontContent *truetype.Font, text string, fontSize float64
 		totalHeight = int(fontSize)
 	}
 
+	// 单行文本情况下，确保有足够的空间容纳文本底部
+	if len(lines) == 1 && len(lines[0]) > 0 {
+		// 获取最低的descender值，确保有足够的垂直空间显示字符底部
+		descenderSpace := int(fontSize / 4)
+		totalHeight += descenderSpace
+	}
+
 	// 创建图像
 	rgba := image.NewRGBA(image.Rect(0, 0, maxWidth, totalHeight))
 	draw.Draw(rgba, rgba.Bounds(), image.Transparent, image.Point{}, draw.Src)