Abstract: New types of saturable pulse transformers (SPTs) with multiple batches of windings in parallel and coaxial cylindrical conductors are presented. The new SPT can be employed as the transformer and magnetic switch simultaneously for pulse capacitor or high-voltage pulse modulator of several hundred kV range. The SPT which has important features such as auto-resetting of core, high step-up ratio and low saturation inductance, achieves a compact integration of common transformer and magnetic switch. In the SPT, the physical suppression effect caused by reversed magnetic coupling mechanism among primary and secondary windings can reduce the saturation inductance of the SPT windings to a level lower than their structure inductances, which helps to achieve a magnetic switch with low saturation inductance. The proposed SPTs were applied in a high power pulse modulator based on a helical Blumlein pulse forming line (HBPFL). When the SPT played as a pulse transformer, the HBPFL could be charged to 200 kV. When the SPT played as a main magnetic switch of the HBPFL, it helped to form a quasi-square voltage pulse with amplitude of 180 kV, pulse duration of 130 ns, rise time of 60 ns. Furthermore, important new technologies and applications of SPT in 100 kV-range compact Marx generator and ns-range synchronization of multiple high-voltage pulses are proposed and demonstrated.