The invention belongs to the field of hydro-power dispatching, and discloses a small hydropower prediction output uncertainty considered day-ahead power generation plan making method of small hydropower and large and medium-sized hydropower station coordination. The method is characterized in that a small hydropower and large and medium-sized hydropower station coordination method is provided by taking the peak regulation electric quantity expectation maximization of a mall hydropower and large and medium-sized hydropower station coupling system as a target to effectively solve a problem of complex hydro-power operation. When small hydropower prediction output uncertainty is considered, the fuzzy clustering and situational analysis methods of the small hydropower prediction output uncertainty are proposed. On the basis, system load is used as an association factor, a successive approximation algorithm and an association search strategy for processing complex time period coupling constraints are mixed to establish a coordination solving frame of a small hydropower and large and medium-sized hydropower station group to coordinate the small hydropower with the large and medium-sized hydropower station and determine the operation plan of the large and medium-sized hydropower station, and the invention exhibits important example values and reference functions to the operation of the large hydropower station in China.