A slide rail mechanism, comprising: a first slide rail assembly and a second slide rail assembly, each of the first and second slide rail assemblies comprising a first rail and a second rail movable relative to each other, and a locking member configured to lock the second rail relative to the first rail at a predetermined position (R'); and a blocking structure of the first rail; and an unlocking handle movably mounted between the first slide rail assembly and the second slide rail assembly; wherein when the unlocking handle is moved from a first position (P1') to a second position (P2'), the unlocking handle is configured to drive the locking member to move in order to unlock the second rail relative to the first rail at the predetermined position (R'); wherein the unlocking handle is configured to be linearly moved from the first position (P1') to the second position (P2'); wherein one of the second rail and the unlocking handle of each of the first slide rail assembly and the second slide rail assembly comprises a first predetermined feature, and the other one of the second rail and the unlocking handle comprises a second predetermined feature, wherein, through interaction between the first predetermined feature and the second predetermined feature, the unlocking handle is linearly moved from the first position (P1') to the second position (P2') along a linear direction so as to provide a driving force (F') to drive the operating member to move the locking member, in order to disengage the locking member from the blocking structure of the first rail; wherein the linear direction is identical to a moving direction of the second rail. a first slide rail assembly and a second slide rail assembly, each of the first and second slide rail assemblies comprising a first rail and a second rail movable relative to each other, and a locking member configured to lock the second rail relative to the first rail at a predetermined position (R'); and a blocking structure of the first rail; and an unlocking handle movably mounted between the first slide rail assembly and the second slide rail assembly; wherein when the unlocking handle is moved from a first position (P1') to a second position (P2'), the unlocking handle is configured to drive the locking member to move in order to unlock the second rail relative to the first rail at the predetermined position (R'); wherein the unlocking handle is configured to be linearly moved from the first position (P1') to the second position (P2'); wherein one of the second rail and the unlocking handle of each of the first slide rail assembly and the second slide rail assembly comprises a first predetermined feature, and the other one of the second rail and the unlocking handle comprises a second predetermined feature, wherein, through interaction between the first predetermined feature and the second predetermined feature, the unlocking handle is linearly moved from the first position (P1') to the second position (P2') along a linear direction so as to provide a driving force (F') to drive the operating member to move the locking member, in order to disengage the locking member from the blocking structure of the first rail;