A method of analyzing biological particles for a biological particle analyzer includes outputting a first detection result when at least one particle has arrived at the first detection area, outputting a second detection result to the control module when the particles have arrived at the second detection area, and determining when to turn on or off the light emission source and outputting a control signal to turn on or off the light emission source according to the first detection result, wherein a control module is configured to calculate a turn-on time according to different particle characteristics and an average velocity of the at least one particle, and the light emission source is turned on only when the at least one particle is being tested during the turn-on time.