Abstract: In this study, how the different noise sources and noise levels affect children's attention and short-term memory was explored by two experiments respectively. In each experiment 30 children from 7-10 years old participated in and they were asked to finish certain cognitive tasks while white noise, air-conditioner noise and road traffic noise were broadcasted randomly. The noise level of each noise source varied from 35 dBA to 65 dBA with a step of 5 dB,which simulated ordinary noise level in indoor conditions. The results showed that compared with task performance,subjective annoyance evaluation was more sensitive to noise effects. Noise level significantly affected children's noise annoyance evaluation whatever noise source was. Children showed a little annoyed when noise level was at 45-50 dBA and showed apparent annoyance when noise level was 60-65 dBA. The adverse effects of environment noise to children's short-term memory was more obvious than that of attention, which showed more complicated of the cognitive process,more adverse effects brought by noise though it needed to be proved by further studies.