Provided is a method for installing undersea production equipment. The method comprises the following installing steps that firstly, the undersea production equipment is lifted from a deck of a dynamic positioning vessel and lowered to a set position under the sea through a crane on the dynamic positioning vessel; secondly, a lifting lug arranged on a balancing weight is connected with a lifting hook of the crane through a snap ring and a sling; thirdly, the crane is started to lower the balancing weight onto the undersea production equipment under the sea and horizontally align the balancing weight with the opening of a guide limiting groove in the undersea production equipment; fourthly, the balancing weight is slowly embedded into the guide limiting groove in the undersea production equipment through the crane, and then the installing process is finished. By means of the method, the undersea production equipment can be assisted in setting in place smoothly; besides, a vertical load can be provided for the undersea production equipment or structure to keep the necessary sit-on-bottom stability of the undersea production equipment; the problem that the undersea production equipment can not settle in place smoothly and has poor sit-on-bottom stability in the existing installing process is solved; meanwhile, the installation cost is greatly lowered.