为研究气体密度对多色激光诱导空气等离子体拉丝辐射太赫兹波的调控作用，建立了由激光拉丝辐射太赫兹波的理论模型。该模型可描述太赫兹波的产生和随后的传输过程，基于该模型和仿真计算，研究了气体密度对太赫兹辐射的影响。结果表明，气体密度会影响激光拉丝的瞬时电流分布与太赫兹波的传播相位，进而影响激光拉丝的太赫兹辐射强度，使太赫兹辐射能量随气体密度的变化呈现非线性变化。该理论研究对激光拉丝物理过程的认知具有重要的参考意义。

In order to study the effect of gas density on the terahertz wave radiated by multi-color laser-induced air plasma filament, a theoretical model of terahertz （THz） generation from a laser-induced air plasma filament and the subsequent propagation process is established. Based on the model and simulation, the influence of gas density on terahertz radiation is studied. The results show that the gas density will affect the transient current distribution of laser filament and the propagation phase of THz wave, then affect the THz radiation intensity of laser filament, and make the THz radiation energy change nonlinearly with the gas density. The theoretical study is of great significance to the cognition of the physical process of laser filamentation.