In this paper the structural mechanism of the gold - lixiviant complex is investigated. The results show that there are two common characteristics in the outer orbitals for all the gold lixiviants: a) a (Y -type of HOEO to form the L-*Au co-ordination bond, and b) a it type f LUEOs, with symmetry the same as that of 5d orbitals of Au, to form L<-au back donating bond. by applying this structural theory a new gold lixiviant, csut(l), was obtained and it is a non-toxic compound with vast of primary materials and good chemical stability. the experimental results show that csut(l) can be combined with many oxidants and the optimum leaching ph is 9 -10. the comparison tests reveal that csut(1) gives similar extraction of gold to that of cyanide but its leaching rate is faster than that of cyanide. gold may be recovered from the csut(l) pregnant solution of carbon adsorption, magchar adsorption and zinc precipitation.>