In order to predict accurately the leakage rate of liquid sheet in pintle injector,the relative deformation models of a liquid sheet and a liquid jet were established,based on the analysis of a spray field structure of a pintle injector element,and by combining with three methods of theoretical derivation,numerical simulation and experimental research. Taking the deformation of liquid sheet and liquid jet into consideration,the models of actual blocking rate and actual leakage rate were established for the first time by introducing coefficient of interaction to characterize the interaction between multi-injector units. Through multi-parameter verification of the numerical simulation and experimental data,the results showed that the predicted values of theoretical model were consistent with the numerical simulation and experimental data. Under the interaction of liquid sheet and liquid jet,the main causes of the deformation of liquid sheet and liquid jet were respectively a flow of liquid sheet around liquid jet and a transverse broadening of the root section caused by an asynchronous movement of the position of the front and rear edges at the root of liquid jet. Besides,the larger effective momentum ratio meant the greater relative deformation of liquid sheet and the smaller relative deformation of liquid jet. For the geometry structure with a certain blocking rate,the results showed that the leakage rate increased with the increase of the effective momentum ratio,and the increasing trend was fast first and then slow. The actual leakage rate was less than the geometric leakage rate,because the actual blocking rate was larger than the geometric blocking rate due to the deformation of liquid sheet and liquid jet. In addition,it was found that the leakage rate was only related to the dimensionless parameters characterizing the flow field structure (effective momentum ratio) and the geometry structure (ratio of sheet thickness to jet diameter and blocking rate),independent of the absolute value of injection velocity. The constant coefficients in the model were given for the engineering design prediction,providing an important guiding significance for considering the thermal protection of pintle tip in the early stage of design.