With the further development of the complementary metal-oxide-semiconductor (CMOS) technology and the silicon-germanium (SiGe) epitaxy technology, SiGe bipolar CMOS (BiCMOS) low noise amplifiers (LNAs) are widely used in the first level of radio frequency (RF) transceiver system in space. The core part of SiGe BiCMOS LNA is SiGe heterojunction bipolar transistor (SiGe HBT) which naturally possesses excellent temperature characteristic and favorable build-in total ionizing dose and displacement damage resistance without any radiation hardening. However, the single event effect caused by the transient charge collection is the bottleneck problem, restricting its application in space. In this work, laser microbeam experiments were carried out on a SiGe BiCMOS LNA in which the sensitive region of single event effect was located. The experimental results indicate that the transient charge collection of SiGe HBT is the main reason of the single event effect of SiGe BiCMOS LNA. TCAD simulations show that the ionization track caused by ion incident in CMOS region will cross the deep trench isolation (DTI) structure, generate electron-hole pairs in SiGe HBT region and cause transient charge collection. The circuit simulations by ADS show that the peak value of the transient voltage will drop sharply when the SEE pulse transient voltage crosses the capacitor between the first stage and the second stage, which indicates that the capacitor plays an important role in transmitting the transient pulses caused by single event effect. The experimental and simulation results in this work provide technical support for radiation hardening by design (RHBD) of the single event effect of SiGe BiCMOS LNA.