In recent years, the proportion of low permeability reservoirs development is becoming larger and larger in the oil and gas exploration field of our country. Water flooding is the most important way for low permeability reservoirs' effective development. In order to improve the effect of the water flooding development, a lot of low permeability reservoirs are infilled well pattern to enhance oil recovery. This paper deals with the study of effect evaluation of low permeability reservoir by infilling well pattern. The main content is divided into two sections: 1) In order to achieve the best results of oilfield development, different infilling pattern are designed, and then the best program is selected according to the principle of well pattern thickening; 2) After thickening the well pattern, according to the selection principle of oil field development effect evaluation index, an oilfield development indexes system is filtered, and then assess on the impact of development, finally, the oilfield development can be evaluated by predicting the main development index.