The powder gun is a conventional device for accelerating a projectile commonly chosen for research owing to its wide range of lauching velocities, good repeatability and flexible work environment, and is widely used in studies of high pressure physics, mechanical properties and dynamic responses of materials. However, as the traditional powder gun uses powder as the energy source, it suffers from the disadvantages of comparatively heavy molecular weight and low sound velocity, poisonous products, requirement of special conditions for transportation and storage. In this work we developed a noval hyper-velocity one-stage gun, whose driving energy is supplied by the gaseous chemical reaction, and whose highest velocity in projectile-launching reaches 2.74 km/s. In addition, we developed a ballistic model and calculated the velocities of projectiles, which are in good agreement with the experimental data. This novel technology is inexpensive, free from use of powder and environment-friendly.