Power tool with replaceable blade

A power tool, comprising:

• a housing;
• a motor positioned in the housing;
• a transmission mechanism positioned in the housing and driven by the motor;
• a fixed blade fixed to the housing;
• a movable blade rotatably connected to the fixed blade through a shaft, the movable blade being connected to the transmission mechanism such that the transmission mechanism is capable of driving the movable blade to perform a cutting motion;
• a quick-locking device arranged on the housing for locking the movable blade, the quick-locking device comprising a quick-locking spanner which is switchable between a locking position where the movable blade is locked and connected with the transmission mechanism and a release position where the movable blade is released to be detachable from the transmission mechanism;
• a control circuit for controlling the motor;
• a main switch for powering on/off the motor, which is electrically connected to the control circuit;
• and
• a safety device capable of controlling the control circuit to be conducted or non-conducted in cooperate with the main switch, if the quick-locking spanner is in the release state, the control circuit is non-conducted result from the safety device, so that the movable blade is prevented from moving, if the quick-locking spanner is in the locking state, the control circuit is conducted when the main switch is turned on.