The invention discloses a phase sensitive detector and a phase sensitive detection method based on a frequency multiplier and a sampling holder. The phase sensitive detector includes a forcing function generator, a zero-crossing comparator, the frequency multiplier, a sampling pulse generating circuit, a first to fourth sampling holder, a first subtracter, and a second subtracter. The first subtracter is connected to the first sampling holder and the second sampling holder, and is used for subtracting an output signal of the second sampling holder from an output signal of the first sampling holder to obtain a vertical phase signal. The second subtracter is used for subtracting an output signal of the fourth sampling holder from an output signal of the third sampling holder to obtain a horizontal phase signal. The phase sensitive detector can carry out signal collection on to-be-detected signals at a fixed phase point through the zero-crossing comparator, the frequency multiplier, the sampling pulse generating circuit and the sampling holders, and then output the vertical phase signal and the horizontal phase signal through the subtracters and a low pass filter. Therefore, the phasesensitive detector effectively improves the detection precision and stability and is simple in structure, and the realization is easy.