The porosity of core samples or geological samples plays a great role in the research on ore-forming fluid. Considering the defects of traditional rock porosity measuring or calculating methods which are hardly capable of obtaiing the internal and original information of rock samples, the authors utilized the industrial computed tomography technology to analyze the porosity of core samples, which can intuitively present object density distribution or structure in the form of digital images. Based on CT images of core samples, the authors used modern digital image processing method composed mainly of edge detection and threshold segmentation to carry out measuring and analyzing porosity of core samples from ZK992 well in a certain mining area. The ROI edge of CT images was first detected in the way of wavelet modulus maxima method based on quadric B-spline wavelet, then the ROI of CT images were segmented in the way of an improved Otsu method. The authors not only obtained the porosity values of 10 core samples that range between 1.22% and 5.79% but also drew the conclusion that porosity of core samples increases first and then decreases as sample location becomes deeper. The result of the research shows that the porosity values measured by this method are in accord with the values by experience. This study offers referable value for research on ore-forming fluid and provides a new method or means for measuring and analyzing rock porosity.