The metallogenic background of diamond primary deposits in the Western Shandong Province is not well understood largely due to lack of information on the crustal structure, location of magmatic intrusions, scale and deep structure of faults and their role in the mineralization process. Based on gravity, magnetic and seismic profile data, this paper employs the Parker Oldenburg interface method, power spectrum method and 2. 5D gravity magnetic seismic joint inversion method to obtain information on crustal structure, fracture scale and magmatic intrusion location in the western Shandong. Based on these results, the deep structural background of primary diamond deposit is discussed. The results show that the primary diamond deposits in the western Shandong are distributed in the low value area of regional Bouguer gravity anomaly， the average value of which is lower than -100×10-5 m/s 2, and the middle low value area of magnetic anomaly with a large variation range from -160 to -60 nT. The deposit is located in the gradient zone with dense contour lines of Moho surface and Live inside, the transition zone between the stable area and the activated area. The depth of Moho surface is about 31. 2~32. 2 km, and the Live inside depth is about 27. 5~30 km. The NW trending faults in the distribution area of the deposit are all over 20 km deep e. g. the 35 km deep Mengshan fault reaching the upper mantle, the 28. 5 km deep Xintai Duozhuang fault reaching the inner part, and the 20. 5 km deep Taishan Tongyedian fault. Formed in the Paleozoic and influenced by the Mesozoic extensional structure, the kimberlite had been gradually uplifted and denuded by NW trending faults until it was exposed at the surface. The gradual decrease of diamond grade from south to north is the result of the large uplift in the north and the denudation close to the root of kimberlite, indicating that there is a great potential for prospecting in the southern ore belt.