Abstract: The natural neutron ambient dose equivalent rate was surveyed by using neutron ambient dose equivalent rate meter. According to the analyzing results, at the location with altitude range 2 000—5 000 m in Tibet autonomous region, the measured value of natural neutron ambient dose equivalent rate was higher than that at sea-level point and it would be 2 times larger when the altitude value increases 1 280 m, and the buildings could result in obvious shielding effect.

Key words: high altitude, natural neutron, ambient dose equivalent rate, effective dose rate, tibet