Master equation of density operators in laser process can be concisely solved by virtue of thermo-entangled state representation.We consider the case in which one model light field in the two-mode squeezed vacuum state evolves in a laser channel.The evolution formula of the field density operator is given in the two-mode squeezed vacuum state initially.Its nonclassical properties,such as squeezing effect,anti-bunching effect,the violation of Cauchy-Schwartze inequality and the entanglement property between two modes,are investigated.Numerical results show that its nonclassical properties are weakened with the increase of dissipation time,until it disappears.On the other hand,its nonclassical properties are strengthened with the increase of squeezing parameter.