Dim base64 As String = "data:image/png;base64,xxx"
'其实应该根据image/png来提取扩展名,懒得写了,反正看图软件都能打开
Dim pic As String = "D:\123.png"
'需要去掉data:image/png;base64,这类前缀,也就是只要逗号后面的内容
Dim bytes() As Byte = Convert.FromBase64String(base64.Substring(base64.IndexOf(",") + 1))
'写入到指定文件
System.IO.File.WriteAllBytes(pic, bytes)