A new method has been developed for rapid field determination of 0. 010-50μg-g silver. The method consists of two independent yet correlated parts: one is Ag-TMK-SDS tribasic complex light-guide colorimetric determination methood for directly determining 0. 25-50μ/g silver,and the other is mercapto group isolation and enrichment micrcbead-separating colorimetry for determining 0. 010-0. 25μg/g silver. These two parts can be comploted successively in the same test liquid.The former has a detection limit of 0. 006μg/ml (k= 3), and for determining silver in copper, lead and Zinc standard ore samples GSO-Cu-1 (containing silver 3. 81μg/g), GSO-Ph- 1 (containing silver 14.7μg/g) and GSO-Zn-1 (containing silver 13. 5μg/g), RSD(n =11) values are 1.6%, some 3.7%and 3. 4 % respectively; the latter can detect 5 ng/g silver, and for determining silver in geochemical standard sample GSD-3 (containing silver 0. 5μg/g), RSD (n=11) is 6. 6 %. Tee method is fairly simple, convenient, accurate and sensitive. With a light-guide colorimeter, the determinations are remarkably improved in accuracy and precision, being equivalent to results obtained by atomic absorption method, and this suggests that the method has a bright future ill application.