Abstract: Ground Base Positioning System has poor geometric diversity due to fixed base station position, and that will cause problems in using LAMBDA to solve integer ambiguity. To solve this problem, self-differential two-way ranging technique has been proposed by using  the two-way measurement to build a formula to eliminate clock errors. As it got rid of the time errors, we use the self-differential two-way ranging measurement as an alternative to double difference measurement, combining with three-carrier ambiguity resolution algorithm to solve the ambiguity. Experimental result on a pseudolite platform shows that this method can achieve fast single-epoch integer ambiguity resolution.