A large scale ships comb slideway side launching skew detection method comprises the following steps: step one, a portal crane(1) and a gantry crane (2) are used to hoist assembly manufacturing components to fold finished ships; step two, berth bogie (3) is used to transport the finished ships to a slipway (8); step three, the finished ships on the berth bogie (3) are unloaded to an inclined launching poppet (5) with altitude difference by a self hydraulic pressure system; step four, the finished ships on the inclined launching poppet (5) are unloaded in water by a winch(4); a ship launching operation system controls the operation of the winch (4). The deficiency that the comb slipway side launching can not be used for the existing large ships is overcame, and ship launching is transferred from the traditional management to the modern scientific standard management by the invention, thus ensuring the safety, increasing the efficiency, reducing the cost and simplifying the maintenance. The invention also discloses a comb slipway side launching skew detection control system using the above detection method.