Abstract: Yongning area has been classified as the fourth diamond metallogenic belt in Liaoning Province due to the discovery of primary diamond. However, the diamond source has not yet been determined so far, and it is necessary to reinforce the study of the indicator minerals associated with the diamond. The compositions of chromite selected from the diabase in Panjiagou area in the eastern Yongning area were analyzed by electron microprobe, and they are compared with the chromite from typical kimberlite pipes in Liaoning Province to explore chromite genesis and the relationship with diamonds. According to the particle sizes, morphology, and melting erosion characteristics in the back-scattered electron images of chromite samples and the composition feature of high Cr, rich Mg, low Al and poor Ti through electron probe micro analysis, the authors speculated that the chromite come from mantle xenocryst, belonging to chromite subclass, which is mainly mafic-chromium-aluminium- ferrum subspecies and mafic-chromium-aluminium subspecies. The calculated formation temperatures of the chromite are 1 252~1 307 ℃, which is consistent with the reported formation temperatures of the chromite in Wafangdian kimberlite, and is also closed to the formation temperature of diamonds. It indicates an affinity relationship between chromites and diamonds, and great potential for diamond prospecting in the diabases of Panjiagou area. This study is significant for the exploration of primary diamond deposits and the identification of the diamond sources in Panjiagou area.