Four sections synchronous expanding and contracting hydraulics cylinder is a new type multisection hydraulics cylinder, it has many special properties. Comparing with other general type multisection hydraulics cylinder, it could achieve the synchronous actions of the multisection hydraulics cylinder. Therefore, it has a high transmission rate. It has a little impact and libration and works steadily. With accurately using, it could improve the properties of hydraulic system and efficacy of hydraulic equipment. The basal structure and the principle of four sections synchronous expanding and contracting hydraulics cylinder are detailedly discussed in the article. The primary parameters about hydraulics cylinder, such as pressure and speed etc, are analyzed. The author also concludes the primary properties of the four sections synchronous expanding and contracting hydraulics cylinder in this article.