Utilizing single-photon photo-association with the enhancement of the resonant coupling effect,we have achieved ultra-cold rubidium molecules with a high number density >5.2 × 1011 cm-3 that provides a new efficient approach toward molecular quantum degeneracy.Meanwhile,the inelastic atom–molecule collision was utilized as a new detection mechanism for ultra-cold molecules.This method is based on the conventional atomic absorption image technique and required no additional laser or imaging system.Because the molecules are observed through the co-existing atoms,the non-destructive imaging of the atomic cloud can be adopted for in situ observation of ultra-cold molecular dynamics.Such a molecule-atom collision can also been used for our future experiments on the ultra-cold molecule-atom collision under magnetic field and ion-atom collision,where the direct detection of molecules and ions is not easily accessible.