用最笨的方法，反算代入法，代一个波动率去算期权价格，再对比当前价格，由于波动率和价格是单调增关系，适当调整到价格附近的时候，可以用两点线性夹逼出近似值。。

同求~

Function ImpliedCallVolatility(UnderlyingPrice, ExercisePrice, Time, Interest, Target, Dividend)
High = 5
Low = 0
Do While (High - Low) > 0.0001
If CallOption(UnderlyingPrice, ExercisePrice, Time, Interest, (High + Low) / 2, Dividend) > Target Then
High = (High + Low) / 2
Else: Low = (High + Low) / 2
End If
Loop
ImpliedCallVolatility = (High + Low) / 2
End Function
Function ImpliedPutVolatility(UnderlyingPrice, ExercisePrice, Time, Interest, Target, Dividend)
High = 5
Low = 0
Do While (High - Low) > 0.0001
If PutOption(UnderlyingPrice, ExercisePrice, Time, Interest, (High + Low) / 2, Dividend) > Target Then
High = (High + Low) / 2
Else: Low = (High + Low) / 2
End If
Loop
ImpliedPutVolatility = (High + Low) / 2
End Function

谢大神。

大神好啊，我刚看了你的回答，我有点不明白啊，function calloption的系数设置里Volatity是怎么取值的呢
比较菜啊，望求大神给予解答啊

你去找些迭代法的资料就知道了

谢大神