The invention belongs to the technology of high-precision angle measurement, and relates to a high-precision angle measurement device based on a spatial four-frequency differential laser gyroscope, and an installation calibration method for the high-precision angle measurement device. The device comprises the spatial four-frequency differential laser gyroscope, a control circuit therefor, a high-speed control and collection circuit, and a computer. The spatial four-frequency differential laser gyroscope is disposed on a to-be-measured rotating shaft through a transition plate, and is connected with the high-speed control and collection circuit through the control circuit, wherein the high-speed control and collection circuit is connected with the computer. The device carries out the integration of an angular velocity component projected on a sensitive axis of the gyroscope, obtains the corresponding rotating angle information, then carries out the calibration of components of a calibration factor of the gyroscope and an inertial space angular velocity on the sensitive axis of the gyroscope, and finally calculates the rotation angle of the to-be-measured rotating shaft through measuring the number of pulses, outputted by the gyroscope, in the rotating process of the to-be-measured rotating shaft. The device is simple in installation, and has little crosslinking with the measured rotating shaft. The device is highly dividable in calibration factor, is high in angle measurement precision, is large in dynamic range, has no counter moment for a measured carrier, is small in temperature factor, does not affect the structure or composition of the measured load, and is better in practical application value.