System-in-Package (SiP) is an important development direction of advanced integrated circuits (ICs) , serving as significant approach to achieve breakthroughs in the domain of integrated circuits. The application of SiP in radiation environments necessitates a thorough investigation in radiation effects. This paper presents the research progress on radiation effects of SiP, focusing on its response to transient γ radiation and electromagnetic pulse (EMP) effects. The key researches include: 1) experiments on the effects of transient γ irradiation; 2) simulations on the coupled electro-thermal-mechanical behavior under transient γ irradiation; 3) joint simulations on power- and signal-integrity to γ irradiation radiation; 4) experimental injection studies on EMP effect; 5) simulations on EMP effects; 6) software fault injection and quantitative assessment techniques. These studies have disclosed the phenomena, laws, and mechanisms associated with the SiP's exposure to transient γ irradiation or EMPs, providing essential data for radiation hardening of SiP and proposing effective hardening-design methodologies. Lastly, this paper demonstrates the faced challenges and future research directions.