Due to marine service environment of subsea pipeline and pipeline structure, only in—line inspection can be adopted to inspect steel pipeline body. In-line inspection used for subsea pipeline mainly includes three inspection techniques and analyzed are the techniques. According to such characteristics of subsea pipeline as small radius of turning circle and existence of the riser and multiphase flow, proposed is the determination method of in-line inspection techniques: selection of specific inspection technique according to characteristics of subsea pipeline, addition of wax and dispersing agent into subsea pipeline during in-line inspection in order to prevent sphere pig from being blocked, trying to pass the pig for preliminary pigging, mechanical pigging operation and intelligent in-line inspection. Feasibility and risk analysis shall be performed before selection of specific inspection technique and corresponding emergency measures shall be prepared for abnormal conditions so as to minimize risks of subsea pipeline in—line inspection.