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Based on the recovery feature, oil and gas relative permeability law and driving mechanism of foamy heavy oil reservoirs, inflow performance relationship of horizontal wells in this kind of reservoirs was studied using multi-component numerical simulation and reservoir engineering methods. A dimensionless IPR equation of horizontal wells in foamy heavy oil reservoirs was also presented. Applying foamy oil multi-component numerical simulation, the IPR curve of horizontal wells in foamy heavy oil reservoirs was obtained: when the average formation pressure is high, the right end of the IPR curve is slightly upturned which shows foamy oil characteristics; with the decrease of average formation pressure, the characteristics of conventional solution-gas-drive reservoirs begin to appear. After comparing the dimensionless IPR curve of foamy heavy oil reservoirs with that of conventional solution-gas-drive reservoirs, it was found that: when dimensionless pressure is high, for both of these two kinds of reservoirs, dimensionless pressure and dimensionless oil production basically display linear relationship; when dimensionless pressure is low, the right end of the IPR curve of foamy heavy oil reservoirs is slightly upturned and that of conventional solution-gas-drive reservoirs is downturned. The relative error between the oil production calculated by the dimensionless IPR equation of horizontal wells in foamy heavy oil reservoirs and actual oil production is less than 13%. This research result can be used to direct the development of foamy heavy oil reservoirs. Key words: foamy heavy oil, horizontal well, inflow performance, IPR curve