【Objective】Through creating and modifying the maize populations， the maize germplasm base was amplified in order to provide new germplasm to Guangxi corn breeding programs. 【Method】According to the combining ability test， inbred lines’ pedigree analysis， and relevant breeding requirements， the 37 and 26 inbred lines were used to respectively create two maize based populations GZPA and GZPB， and the simplified and modified HS reciprocal recurrent selection methods were applied on the two genetically improved populaions to analyze their agronomic traits and genetic gain. 【Result】After improvement， the average yield increase of two hybrid populations in four experimental sites was 7.70%， in which the silking days， ASI days， ear length， ear diameter， rows per ear， kernels per row， seed setting rate， and 1000-grain weight all displayed advantageous gain to some extent. The average yield of GZPA and GZPB was 5.37 and 4.85%， respectively. The population GZPA’s silking days， ASI days， and seed setting rate showed negative gain； other traits， on the other hand， exhibited positive gain， and that of the plant height， ear diameter， and rows per ear showed significant difference. The population GZPB’s silking days， ASI days， ear length， ear diameter， rows per ear， and kernels per row all displayed positive gain， while all other traits displayed negative gain. The variance coefficients of the two populations before and after improvements exhibited little changes. 【Conclusion】After the improvements were obviously observed from the two groups applied with the modified HS reciprocal recurrent selection method， the two groups still showed large genetic variations， which could be enhanced further.