Olefin polymerization method and system

An olefin polymerization method, comprising the following steps:

• S1, compressing and condensing circulation gas flow comprising an olefin and a condensing agent exported from an outlet of a second reactor to obtain a gas-liquid mixture;
• carrying out gas-liquid separation of the gas-liquid mixture to obtain a gas material and a liquid material, wherein the liquid material comprises a first liquid material and a second liquid material having the same or different compositions;
• S2, conveying the gas material and the first liquid material back to the second reactor for circulation, introducing the second liquid material into a first reactor, simultaneously conveying ethylene and a catalyst into the first reactor, and polymerizing the olefin in contact with the catalyst in the first reactor to form a mixture comprising a first polyolefin;
• S3, leading out the mixture comprising the first polyolefin from the first reactor and separating the mixture into at least a first mixture and a second mixture having the same or different compositions;
• conveying the first mixture back into the first reactor after heat exchange, and pumping the second mixture into the second reactor;
• and
• S4, performing polymerization reaction of the olefins in the second mixture, the gas material and the first liquid material in the second reactor where the olefins are in contact with the catalyst to generate a second polyolefin, thereby forming a polymerization product comprising the first polyolefin and the second polyolefin.