Abstract: A method for measuring drop time of a control rod cluster integrated with a rod position measurement device is provided, wherein the method is used to measure the drop time of each control rod cluster, and includes: Si, monitoring a voltage Ua of coils in Group A to capture a rod cluster drop signal; S2, searching a point (tmax, Vmax) with a maximum drop speed or with a local maximum drop speed; S3, retroactively calculating, from tmax, an end of a time period T4 when the control rod cluster starts to drop; S4, retroactively searching, from a minimum value point of a drop reference signal DROPref, a start of the time period T4 when the drop reference signal DROPref drops from a maximum value to 33% thereof; and S5, determining, from tmax forward, a time point t6 when a drop speed of the control rod cluster is lower than 0.