A spindle motor component of hard disk with composite coating layer and a composite coating method hereof. The checking if a current version of the information is already stored in a storage unit. In particular embodiments, the modified ratio In is determined in accordance with formula or formula where I0 is the base ratio, RTP is the designed performance, T is the revenue, P is the total prizes and Q is a control variable. Also, upon judging that the headphone plug is connected with the headphone jack, the function of an equalizer switch is disabled.