导出了磁绝缘传输线振荡器 (MILO)中辐射场的非线性演化方程 ,并讨论了在临界值点附近可能出现非线性不稳定解的条件。结论是 :(1)非线性增长速率与线性增长速率的比值g <1.2 ,且远离 g +γ =1(γ为非线性相位增长率与线性相位增长率的比值 )点时 ,出现非稳定解的失谐量临界值很小 ,而线性增长速率临界值临界值很大 ,容易出现非稳定解 ;(2 )当 g≥ 1.2时 ,任意小的失谐量都可以使场出现非稳定解 ;(3)线性增长速率越大 ,越不容易出现非稳定解 The nonlinear evolution equation of the radiation field in the MILO is deduced and the conditions of nonlinear instability solution near the critical point are discussed. The conclusions are as follows: (1) The ratio of nonlinear growth rate to linear growth rate g <1.2, and away from g + γ = 1 (γ is the ratio of nonlinear phase growth rate to linear phase growth rate) The critical value of the detuning threshold is very small, but the critical value of the linear growth rate is very large, which is prone to instable solution. (2) When g≥1.2, any small detuning can make the field appear unsteady solution; (3) The larger the linear growth rate, the less likely to have unstable solutions