Siemens ultra-supercritical (USC) turbine has the characteristics of unique structure, compact arrangement, quick start-up, stable operation, high efficiency and a lot of protection that increases the trip probability. According to the unconventional trip protection conditions, this paper analyzed probable cause, adoptable measures and possible consequence of the turbine trip, and suggested to reserve, modify and delete some trip protection conditions, which could provide some references for the units protection conditions setting.