Abstract In modern precision engineering field, micro/nano-positioning stage has been widely applied in various situations, such as atomic force microscopy, micromanipulation of biological cells, micro-assembly of robots, and so on. It owns the merits of high accuracy and fast response. But some limitations exist, such as big overall size, restricted travel, and complex control strategy. So, the research topic is concentrated on mechanical design with compact overall size, large travel, high decoupling ratio and easy control or even no control. Firstly, to reduce the dependence on large force actuator and protect the operated object from overloading, the constant-force mechanism is adopted. A novel compliant gripper with compound constant-force mechanism is designed to obtain the constant-force property and test the performance. Then, another compound constant-force parallel gripper is designed to complete the movement along 2 DOF. As the movement of the proposed mechanisms is still in a plane, the spatial 3-DOF stages are adopted. Then, two parallel stages of 3-DOF are proposed. To obtain large travel, a new 3- DOF spatial flexure parallel micro-positioning stage is designed. And a novel 3-DOF large-stroke parallel micro/nano-positioning stage is designed to reduce the rotational motion. Finally, to get an advanced mechanism which has 3-DOF’s movement and constant- force property, two constant-force parallel mechanisms are proposed. A novel 3-DOF active constant-force parallel stage is designed to release the dependency of large force actuator. And a novel 3-DOF passive robotic end-effector with adjustable constant force is designed to protect the operated object. The designed constant-force parallel stages can be applied in positioning operation such as biological manipulation, micro-surgery, mechanical assembly, etc.