The invention discloses an ellipticity measurement device for a subsea pipe, and the device comprises a fixed frame and one or more circular measuring rings arranged at the periphery of the subsea pipe in a sleeving mode. The measuring ring is arranged in the fixed frame, the peripheral side face of the measuring ring is connected with the fixed frame, and an inner channel of the measuring ring forms a testing channel for the subsea pipe to pass. The device is used for quickly measuring the ellipticity of the subsea pipe, especially the ellipticity of the cut end of the subsea pipe, so that amechanical connector can be smoothly mounted at the cut end of the subsea pipe in subsequent procedures, and the problem that the connector is unqualified in sealing due to the fact that the ellipticity of the subsea pipe does not meet requirements in the subsea pipe maintenance process is effectively prevented. The device is simple in structure and easy to operate, manual operation can be achieved, manual operation can be replaced with ROV operation, the problem of subsea pipe cutting end ellipticity measurement in the deepwater subsea pipe maintenance process is solved, and the deepwater subsea pipe maintenance accuracy and efficiency are improved.