The invention relates to a transient electromagnetic 
logging instrument which comprises a shell, a circuit module and an electromagnetic probe 
system, wherein the circuit module is arranged in the shell, and the electromagnetic probe 
system is connected with the circuit module. The circuit module is sequentially connected with a power 
voltage regulator module, a PWM (
pulse width modulation) module, a high-power isolating 
transformer bank and a power conversion module through a direct-current power supply to form a direct-current power supply circuit and a main 
control circuit taking a 
digital signal processor as a core, and a communication 
bus, a power 
bus, a 
control bus and a data 
bus are arranged on the periphery of the main 
control circuit. The electromagnetic probe 
system comprises a transmitting coil and a plurality of receiving coils, wherein the transmitting coil is provided with a 
magnetic core. The instrument detects casing damage and effectively measures the formation resistivity of an 
open hole well and a cased well in a non-
contact mode. High-power transient excitation is realized by the aid of internal iron cores of the coils, the excitation intensity of a transient 
electromagnetic field is improved, and the formation resistivity is finally obtained by necessarily graduating and 
processing measured original signals.