Pushing device for extraction of formation fluid

The invention discloses a pushing device for the extraction of formation fluid, which comprises a main cylinder, and the bottom of the main cylinder is provided with an axially extended central guide rod, on which a first pushing piston and a second pushing piston are sequentially sleeved; the sidewall of the main cylinder is provided with an extension oil port, a formation fluid oil port and a retraction oil port, the extension oil port is communicated with an extension oil chamber of the main cylinder through an extension oil passage axially arranged in the sidewall of the main cylinder, the formation fluid oil port is communicated with a fluid inlet of the central guide rod via a fluid passage, the fluid passage consists of a first passage a second passage and a third passage, wherein the first passage sequentially runs through and is axially arranged in the sidewall of the main cylinder, the second passage is radially arranged in the bottom of the main cylinder, the third passage is axially arranged in th