A transmission and positioning mechanism includes a guiding assembly, a driving assembly and a positioning assembly. The guiding assembly includes two sliding rails, a transmission belt, a plurality of sliding members. The sliding members are slidably disposed on the sliding rails. The positioning assembly includes a transmission rod, a positioning rod connected to the transmission rod, a positioning block sleeved on the positioning rod, a driving rod sleeved on the transmission rod. The driving rod defines a spiral slots and at least one limiting slot. The driving assembly is connected to the positioning assembly and rotates the transmission rod, the positioning rod and the driving rod, the spiral slot engages one of the plurality of the sliding members to move other sliding members to the at least one limiting slot and the positioning blocks, and the at least one limiting slot and the positioning blocks latch the sliding members.