Abstract: It is difficult to forecast the production capacities of stepped horizontal wells when producing multiple reservoirs at multiple sections. On the basis of the relevant theories such as seepage mechanics, engineering fluid mechanics, reservoir engineering and numerical analysis, a new detailed coupled model of stepped wells and thin interbedded reservoirs was established by utilizing discretization processing and considering factors such as anisotropy, filtering interference, pipe flow pressure drop and contamination caused by drilling and/or completion. This productivity calculation model of multilayer commingled production of stepped wells has a unique solution. Taking a three thin interbedded reservoir as an example, we analyzed with this model the wellbore radial flow rate, wellbore flow and wellbore flow pressure distribution rules of stepped horizontal wells. Numerical simulation results showed that flow friction in the wells should not be overlooked, and the stepped horizontal well flow rate distribution presented the shape of a high-order polynomial, the flow rate distribution adhered to cubic polynomial law, flow pressure distribution stayed within parabolic limits, and pressure dropped faster at the heel section. The entire well production calculated by this model is just 1.79% less than Joshi’s. It demonstrated that the calculation results for production were reasonable and provided a new method for productivity prediction of stepped horizontal wells.