Neutron radiation was specially correlated with the type and the power of the radio frequency (RF) heating for deuterium plasma on HT-7 tokamak. We hare researched the production mechanism of the fast neutron under different RF heating conditions by the fast time-resolved neutron flux measurement system make up of BF3 and 3He proportional counters. Lower power of LHW heating was apt to bring abont runaway discharge and produce a mass of photoneutrons. The rate of fusion neutron and the total neutron yield will rapidly increase with the ion cyclotron resonance heating at the special frequencies of (27 MHz and 24 MHz).