Aiming at the problems of high boulder yield,high explosive consumption and poor blasting effect in an open-pit mine with complex lithology in Xinjiang,59 blasting tests for the optimal inter-hole and inter-row delays in rock masses with different blastabilities were carried out on four levels(between 445 m and 595 m) at the east side of the mine.The optimal delays between holes and rows were determined by the shape of blasting pile,ore rock fragmentation and powder factor.The test results show that the blasting pile is flat and the fragmentation is uniform for benches of mudstone with some fine sands when the delays between holes and rows are 5.9 ms/m and 14 ms/m,respectively.For sandstone with part of mudstone lithologic,when the delays between holes and rows are taken as 2.7 ms/m and 14.2 ms/m respectively,the blasting pile shape and fragmentation are reasonable and the boulder yield is low.The test results are applied to the field production of the mine,and the average powder factor and boulder yield are 4.03% and 1.8%,respectively,which are lower than those of previous years.The research shows that reasonable selecting of delay time between holes and rows for complex geological conditions can obtain flat blasting pile and the uniform block size,which can effectively reduce the powder factor,and save costs.The delay time determined in this test can provide important field data for selecting the delay time of mudstone and sandstone mixed bench blasting under the same geological conditions in Zhundong area.