Specific to the difficult detection of product quality or performance parameters in confined spaces, the work aims to design a new 3-PPR parallel-mechanism detecting robot to reduce the horizontal size of the robot and improve the implementation of the detection work. The degree of freedom of the mechanism was calculated by spiral theory and modified Grübler-Kutzbach formula. The forward and inverse kinematics equations of the mechanism were established and solved by closed-loop analytic method. The working space was obtained by MATLAB software and Monte Carlo method. The attitude relationship between the driving joint and the end effector was clear, and the working space was cylindrical and compact, which could meet the requirement of detection accuracy. The three-degree of freedom parallel robot is suitable for carrying out inspection tasks in confined spaces, with stable movement and high reliability, providing a new method for intelligent detection of agricultural products in storage and transportation.