Disclosed are an adapter and a charging control method. The adapter includes a power conversion unit, a sampling and holding unit, and a current collecting and controlling unit. The power conversion unit is configured to convert input alternating current to obtain output voltage and output current, in which the output current is first current with first pulsating waveform. The sampling and holding unit is configured to sample the first current when the sampling and holding unit is in a sampling state, and to hold a peak value of the first current when the sampling and holding unit is in a holding state. The current collecting and controlling unit is configured to determine whether the sampling and holding unit is in the holding state, and to collect the peak value of the first current when the sampling and holding unit is in the holding state.