This paper aims to explore the method of combining constraint elements in the form design of agricultural equipment with virtual reality technology to carry out innovative design, so as to quickly respond to the needs of the target market, improve the success rate of design objects and design quality, and reduce design time. Firstly, the methods of virtual experience, interview survey and word frequency statistics are used to determine the product image constraint positioning in a combination of qualitative and quantitative methods; secondly, the morphological analysis method is adopted to extract the brand style characteristics of the target product, designers are invited to design image geometric forms under the constraints of the image, and the two form a hybrid prototype library; then, the shape grammar is used to form the fusion of the brand style features and the image geometry in the mixed prototype library to complete the main form design; finally, a design environment is build based on interactive virtual experience scenes, and the overall form design and review of the target product under space constraints are completed. With the silage round baler as an example, the effectiveness and practicability of the perceptual engineering combined with virtual reality technology in the form design of agricultural equipment are verified. From the perspective of image, brand style, space constraints and virtual design, a method of agricultural equipment form design under virtual perceptual engineering is proposed. This method effectively improves the progress and success rate of agricultural equipment form design, and provides ideas for product form design in related fields.