After making a detail analyzing on the method of geometric-free phase combination,We know that using this method to detection cycle slip will appears misjudged situation in the condition of high ionosphere delay.In order to solve this problem,We proposed a modified method.we find several optimum interfrequency combination observables,which have long wavelengths,low-noise levels,reduced the first-order and second-order delay of ionosphere.Make a preestimate to the first-order delay of ionosphere use the three frequency observation.And then re-select the cycle-slip detection volume sequence.To validate this method,We use the real observation which under the condition of high ionosphere delay load from IGS.Experimental results show that this method can be realized the real-time cycle slip detection and repair for triple-frequency under conditions of high ionosphere delay.And It has its own advantage on handing of real-time un-differenced cycle-slip.