The electromagnetically induced grating (EIG) effect is theoretically studied under the cold atomic and room-temperature atomic systems, respectively. The study results show that the first-order diffraction efficiencies in the cold atomic system and the room-temperature atomic system can reach 32.5% and 30%, respectively. The two diffraction efficiencies are very close to the ideal diffraction efficiency of a sinusoidal grating. However, as far as the actual condition is concerned, the preparation of a cold atom system is more difficult than that of a room-temperature atomic system. Moreover, the cold atomic system is more complex and requires higher experimental conditions.Therefore, the realization of EIG with room-temperature atoms is more superior. The theoretical studies also indicate that the EIG effect can also occur with low-power signal and low-power probe beams, and the first-order diffraction efficiency is close to the theoretical maximum, which can be used to realize a weak field modulation with another weak field.