Provided is a method for improving the transformation efficiency of soybean, the method comprising: transforming plant cells by using a recombinant vector containing a target gene and a gene encoding a sulfonylurea-type herbicide hydrolase; selectively cultivating the transformed plant cells by externally applying an ALS inhibitor, with the gene encoding the sulfonylurea-type herbicide hydrolase acting as a selective marker; and selecting plant cells which are not killed and/or not inhibited. By adding a selection agent into a proliferation medium and a differential medium by externally applying same in the plant transformation process, the effective screening concentration range of the selection agent is optimized, such that the transformation efficiency and the proportion of positive plants obtained by the progeny thereof are significantly improved; in addition, transgenic plants obtained by means of transformation with the sulfonylurea-type herbicide hydrolase gene acting as the selective marker in the pre
