The invention relates to a preparation method for a film press belt of a greenhouse, and belongs to the technical field of agricultural materials. In order to solve the problem of low strength of an existing film press belt, the invention provides a preparation method for a film press belt of a greenhouse. The method comprises the following steps: moving forwards a plurality of twisted polyester fibre lines which are parallel and located on the same plane under an action of a traction force, and then carrying out heating treatment on the twisted polyester fibre lines through a heating interval to enable the twisted polyester fibre lines to be in a softened state; and then enabling the twisted polyester fibre lines to pass through thermoplastic resin in a molten state, enabling the twisted polyester fibre lines to be integrally compounded with the thermoplastic resin in the molten state, coating the interior of a thermoplastic resin layer formed after the thermoplastic resin in the molten state is cured with the twisted polyester fibre lines to form a flat semi-finished film press belt product, and then carrying out cooling treatment on the film press belt to obtain the corresponding finished film press belt of the greenhouse. The method disclosed by the invention achieves high binding strength and breaking strength.