Abstract: Taking the tight sandstone reservoir of Middle Jurassic Toutunhe formation in Block 4 of central Junggar basin as an example, and based on the data of logging interpretation and formation testing, the lower limits of effective reservoir physical properties in the study area are determined by comprehensive consideration of empirical statistical method, distribution function curve method, formation test method, porositypermeability method, positiveinverse cumulative method and mud content method. The study results show that the lower limit of effective reservoir porosity is 4.52%, the lower limit of permeability is 0.14 mD; the porosity and permeability exhibit a relation of power function and the lower limits of the effective reservoir physical properties decrease with the increase of depth. The weighted average algorithm of the reliabilities of all the methods is used to determine the lower limits of effective reservoir physical properties, which can effectively avoid the randomness and uncertainty of a single method