The invention provides a method for fusing ocean current observation data of an unmanned undersea vehicle (UUV), which comprises the following steps of: 1, obtaining ocean current profile data, when the UUV underwater navigates at a certain depth, obtaining an ocean current profile with a certain water layer thickness at the upper part or lower part of the UUV; 2, filtering the ocean current profile data, filtering the obtained ocean current original data, eliminating a wild value, carrying out smooth correction on a measured random error; 3, carrying out time registering on the ocean current profile data, reducing asynchronous data into synchronous data under the same time moment; and 4, reducing position information of the UUV, starting from one known coordinate position of the UUV to reduce a coordinate position of the next time according to the navigation direction, the navigation speed and the navigation time of the UUV at the coordinate position; and 5, fusing the ocean current profile data, converting longitude and latitude position information obtained from the reduction of the position information into ASCII (American Standard Code For Information Interchange) codes, and inserting into corresponding positions of an ADCP (Acoustic Doppler Current Profiler) data packet. According to the invention, accurate and complete ocean current profile information can be obtained under a geodetic coordinate system.