Abstract: Microbially induced carbonate precipitation ( MICP) is a novel ground treatment solution． In the past，the solution was always injected into saturated sandy soil; however recently，researchers have discovered that the effect and position of the CaCO3 bonding the sand would be different changing with different injection method，and they had great impact in the strength and homogeneity of treated samples． Reverse injection saturated method and unsaturated percolation method were compared． Scanning electron microscope ( SEM) and unconfined compression strength ( UCS) tests were used to estimate the behavior of the samples． The results showed that the samples treated with the unsaturated percolation method had superior quality( an average UCS of ( 19. 7 5. 86) MPa) than the ones treated with the reverse injection saturated method( ( 15. 1 5. 73) MPa) ．