1. College of Earth Sciences, Jilin University, Changchun 130061, China;
2. Research Center of Paleontology and Stratigraphy, Jilin University, Changchun 130026, China;
3. No.1 Middle School in Nanping, Nanping 353000, Fujian, China;
4. Institute of Exploration and Development of Daqing Oilfield Company Ltd, Daqing 163712, Heilongjiang, China

Reservoir space types and controlling factors of alteration of Yingcheng Formation volcanic rocks in Xujiaweizi depression were studied by core data, thin sections and scanning electric microscope. Based on chemical alteration index (CIA), clay mineral test and rock mineral characteristics, the intensity of alteration is divided into three types: weak alteration(CIA<50), moderate alteration(50< CIA< 60)and strong alteration(CIA>60). The types of diagenesis related to alteration include: devitrification, dissolution and filling. It is indicated from this research that more secondary pores were developed with the increasing of alteration intensity, devitrification of matrix and clay mineralization of rocks. Devitrification and dissolution can also improve the reservoir properties. Although cavity filling apparently reduced the reservoir properties, there are intergranular micropores in the infilling of clay minerals, which still has a certain reservoir performance.