The invention relates to a producing method of polyoxymethylene dimethyl ether by partition wall catalytic distillation. The production method includes the following steps: an methylal solution of trioxane enters from an upper feed inlet of a main tower of a partition wall catalytic distillation tower, a raw material methylal enters from a lower feed inlet of the main tower of the partition wall catalytic distillation tower, and the raw materials trioxane and methylal are subjected to an acetal reaction in the middle of the main tower of the partition wall catalytic distillation tower and subjected to vapor-liquid mass transfer; mixed steam obtained from the top of a secondary tower of the partition wall catalytic distillation tower is condensed by a condenser; and a polyoxymethylene dimethyl ether crude product discharged from a reactor of the partition wall catalytic distillation tower enters the middle of a product refining tower for distillation separation, and mixed steam obtain at the tower top is condensed by the condenser to obtain a polyoxymethylene dimethyl ether DMM3-8 product. The production method of the invention integrates a series of acetal reaction and product delighting into the same tower. The equipment has the advantages of high conversion rate, high selectivity, low energy consumption, less equipment investment and the like.