The invention relates to a fibre spreading mechanism by a manipulator, which comprises a plywood tilting mechanism, a plywood jaw opening and closing mechanism, and an air supplying mechanism. The top of the plywood tilting mechanism is connected with one end of the plywood jaw opening and closing mechanism in a transmission manner, and drives the plywood jaw opening and closing mechanism to swing around a shaft; a plywood jaw is arranged at the other end of the plywood jaw opening and closing mechanism, and is driven by the plywood jaw opening and closing mechanism to execute the opening and closing actions; the air supplying mechanism is arranged at the top of the plywood jaw. The fibre spreading mechanism has the advantages that the productivity effect is increased, and the production cost is saved; because a manipulator device is used for automatic fibre spreading, the rhythm is designed to lead one ramie beam to press another ramie beam, the spacing is accordant and equivalent, the stems of the formed ramie stripes are more uniform, and the product quality is increased.