The invention discloses a 
thermal desorption, gas-phase separation and thermal 
cracking system based on ethylation derivation of methyl mercury, comprising a 
thermal desorption part, a gas-phase separation part, a thermal 
cracking part, a gas flowmeter, a Teflon FEP pipeline and a pressure regulating and 
temperature control switch chamber, wherein the 
thermal desorption part comprises a thermal 
desorption heater strip switch, a thermal 
desorption heater strip 
time control switch, a thermal 
desorption heater strip 
pressure regulator, a pressure regulating knob of the thermal desorption heater strip 
pressure regulator, a thermal desorption heater strip and a 
Tenax adsorption 
pipe; the gas-phase separation part comprises a heater jacket, a heater jacket switch, an OV-3 packed column and a heater jacket 
temperature control plate; and the thermal 
cracking part comprises a thermal cracking heater strip switch, a thermal cracking heater strip 
time control switch, a thermal cracking heater strip 
pressure regulator, a pressure regulating knob of the thermal cracking heater strip pressure 
regulator, a thermal cracking heater strip and a 
quartz pipe. The 
system realizes the aim of integration of thermal desorption, gas-phase separation and thermal cracking devices, and simultaneously, each part can be individually operated, thereby saving the analysis time, having low manufacturing cost and greatly reducing experiment cost.