The measurement of coherent elastic neutrino--nucleus scattering (CE$\nu$NS) can test the standard model and explore new physics. REactor neutrino COherent scattering Detection Experiment (RECODE) is a CE$\nu$NS detection experiment aiming at realizing the accurate measurement of reactor CE$\nu$NS using HPGe detectors. This experiment has two HPGe arrays, each consisting of five 1-kg HPGe detectors. It is designed to have a low background (< 2 counts/kg/keV/day), low energy threshold ($\sim$ 1 keVnr), and long-term stability ($\geq$ 3 years). The experimental system will be placed on the ground surface, 25 m away from the reactor core of the Sanmen Nuclear Power Plant, where the neutrino flux is on the order of $10^{13}$ /cm$^2$/s. Herein, the conceptual design, prestudies, and experimental schedule of RECODE are outlined.