The Korea Advanced Institute of Science and Technology (KAIST) Rocket Laboratory, KAIST Satellite Technology Research Center, Naraspace Technology Co., Ltd., and Space Solution Co., Ltd. have formed a project group to develop key systems of a small-scale sounding rocket. 1,000 N class hybrid rocket using 90 wt% hydrogen peroxide as oxidizer and high-density polyethylene as solid fuel was designed to apply to main engine of a demonstrator. Technology of non-pyrotechnic deployment utilizing spring control was developed for the recovery of demonstrator. The rocket avionics was developed for control of main oxidizer valve and non-pyrotechnic deployment, and data acquisition during flight. Based on calculated Mach number from 6 degrees of freedom (DOF) trajectory simulation, the nosecone was designed. Performance and reliability evaluation of thruster, developed technologies of non-pyrotechnic deployment, and rocket avionics were performed by flight tests of demonstrator with a length of 2.7 m, four fins, and diameter of 153 mm. Therefore, in this paper, development process of key systems was described, and results of flight tests and future plans were discussed.