The invention discloses a CPU (central processing unit) load testing method for equipment in a DCS (distributed control system), and relates to the field of nuclear power plants. Two continuous voltage values comprising a voltage value V are searched from waveform voltage values of a rising edge and falling edge of each waveform period of the tested equipment respectively, a higher voltage value is taken as a hopping point of the rising edge or falling edge, time at a coordinate point of the higher voltage value is acquired, and the hopping point of the rising edge is subtracted from the hopping point of the falling edge to obtain the CPU load time of the equipment. In the method, waveform period analysis over the whole tested equipment is realized by utilizing a computer, so low error and high efficiency are achieved; the environment of the tested equipment and influence caused by the tested equipment are taken into full account, and waveform hopping is judged based on adjacent data comprising a high level, so accuracy is high; and a final result is represented by percentage so as to be convenient to compare.