The invention relates to a phase measurement method of a variable exposure time imaging phase shift, belonging to the technical field of optical phase measurement. the method is characterized in that image-collecting software based on a variable exposure time imaging phase shift is established in a computer in an SPR (Surface Plasmon Resonance) imaging detection system which is modulated by a time phase, exposure time parameters including various different parameters, such as exposure time, exposure start time and exposure end time are set, and a phase shift measurement period, a frame synchronization period, an electro-optical crystal synchronization period and an exposure signal period including the exposure start time and the exposure end time are controlled by an FPGA (Field programmable Gate Array) preset in a CCD (Charge Coupled Device) camera to drive a CCD driving circuit so that images are shot one by one by a CCD chip, and the standard deviation of the phase error of p lightoutput by a polarizer is reduced by reducing the standard deviation of a light intensity measurement error in an interferogram which is generated by every phase shift. The invention has the advantagethat the error accuracy of a detected phase is improved.