Tube hydroforming with radial crushing (THFRC) process is particularly applicable to the tube which is difficult to shape due to lack of axial feeding. In this paper, the formability of the circular tube expanded into a triangle cross-section under the simple loading paths is explored by using the numerical simulation. The effect of the forming mode and the loading paths on bulged profile, wall-thickness distribution and the potential fracture location of the bulged tube are analyzed. The results showed that constraint conditions at tube ends have small influence on the bulged profile and wall-thickness distribution. Moreover, the larger the peak value of the internal pressure is, the better material filling ability and higher accurate the tube bulged profile are. Furthermore, the higher forming accuracy, the better material filling ability and wall-thickness distribution are gained in THFRC than those in free hydro-bulging (FHB) process, and they can be obtained under constant than linear pressure loading paths. Finally, the potential fracture location of the bulged tube in THFRC process is quite different from that in FHB process.