To well understand the deep structure environment and mechanism of strong earthquakes occurred in the Tianshan-Mongolia-Lake Baikal seismic belt, an integrated geomagnetic and gravity survey was conducted along the profile from Suhbaatar to Ulaanbaatar to Dalandzadgad in Mongolia. In this paper, petrophysical parameters (bulk density, magnetic susceptibility, intensity of natural remanent magnetization, and Köenigsberger ratio) of 585 rock samples collected from this profile are summarized. Results indicate that significant density contrast of different rocks would result in variable gravity anomalies along the profile. Magnetic susceptibility and natural remanent magnetization of all rocks are variable, covering 3~5 orders of magnitude, which would make a variable induced magnetization and further links to complex magnetic anomalies in ground surface. These petrophysical parameters provide essential constraints on the interpretation of geophysical data and to calibrate geophysical parameters.