Miter saw with folding power-off protection function

A miter saw comprising:

• a base seat unit including a worktable which has a working surface, and a pivot seat which is connected with said worktable, said pivot seat defining a pivot axis;
• a cutting unit including a support arm which is pivotably mounted on said pivot seat about the pivot axis, a saw blade which is rotatably mounted on said support arm to be rotated about a blade axis, a driver which is mounted on said support arm to drive rotation of said saw blade, a trigger which is pivotably mounted on said support arm, and a switch which is mounted on said support arm and which is triggered by said trigger to turn-on and turn-off said driver, said cutting unit being operated to rotate relative to said pivot seat about the pivot axis to rotate said saw blade relative to said working surface among a first working state, where said saw blade is disposed substantially perpendicular to said working surface, a second working state, where said saw blade is tilted relative to said working surface, and a folded state, where said saw blade is disposed substantially parallel to and close to said working surface;
• and
• a safety unit mounted on said support arm adjacent to said trigger, said safety unit including at least one slide slot and a movable pin which is engaged with and slidable along said slide slot, said slide slot having a first slot portion, a second slot portion which is opposite to said first slot portion in a first direction that is substantially parallel to the blade axis, and a curve slot portion which interconnects said first and second slot portions, said safety unit having a retaining portion which is bordered by said curve slot portion and a reference plane that passes through said first slot portion and said second slot portion;
• wherein, when said saw blade is disposed in the first working state to have the blade axis be substantially parallel to said working surface, said movable pin is obstructed by said retaining portion and retained to said first slot portion, and said trigger is operable to trigger said switch,
• wherein, when said saw blade is disposed in the second working state to have the blade axis extending to inclinedly intersect an extension plane of said working surface, said movable pin is obstructed by said retaining portion and retained to said first slot portion, and said trigger is operable to trigger said switch, and
• wherein, when said saw blade is rotated from the second working state to the folded state to have the blade axis extending to substantially intersect the extension plane of said working surface perpendicularly, said movable pin is moved, by its weight, through said curve slot portion, to said second slot portion below said first slot portion, and said movable pin locks said trigger to prevent operation of said trigger for triggering said switch.