The invention discloses an estimation method for parallel mismatch of subarrays of a photovoltaic power station. The estimation method comprises the following steps of: carrying out IV scanning on thesubarrays to obtain IV curves; obtaining theoretical maximum output power P1 of the subarrays according to the IV curve of each string, calculating theoretical maximum output power P2 of string typeinverter subarrays; calculating theoretical maximum output power P3 of centralized type inverter subarrays; obtaining parallel mismatch loss of the string type inverter subarrays deltas and the centralized type inverter subarrays deltac. The estimation method disclosed by the invention has the advantages that IV curves of all strings of the subarrays can be measured and calculated simultaneously,the voltage differences of maximum power points of each string are obtained by testing under same conditions at the moment, so that the mismatch of working voltages among all the strings in the subarrays can be accurately evaluated.