The utility model relates to a conversion and recording device for assisting a mobile phone. The conversion and recording device is assembled on the mobile phone and comprises a first microphone, a second microphone, a recording processor, a memory and a battery, wherein an input end of the first microphone is connected with a telephone receiver of the mobile phone; an output end of the first microphone and an output end of the second microphone are connected to the recording processor; the battery is electrically connected with the recording processor; and the recording processor is electrically connected with the memory. As the conversion and recording device for assisting the mobile phone transmits sound from the telephone receiver to the recording processor through the first microphone and transmits sound from a user to the recording processor through the second microphone, an independent recording function can be realized only by adding the conversion and recording device into the original mobile phone without changing the mobile phone structure. Therefore, original quality of the mobile phone is unchanged and conversion way is unnecessary to change. The conversion and recording device for assisting the mobile phone, disclosed by the utility model, has the advantages of a simple structure, low cost and operation convenience.