The non-classical light at alkali atomic absorption lines is one of the important resources for quantum information networks, and it gets more attentions recently. Because of the unique wavelength of the non-classical light field at cesium D1 line, it has important application prospect in the field of solid-state quantum information networks. Continuous wave single frequency Ti: sapphire laser is used as light source. The 447.3 nm blue laser is generated by the output 894.6 nm laser locked at cesium D1 line via frequency doubling of external cavity. The blue laser is used to pump continue wavelength degeneration optical parametric oscillator, and the nonlinear medium of the oscillator is periodically poled KTP (PPKTP) crystal. Then the simple module quadrature squeezed vacuum light at cesium D1 line is obtained. The threshold of the optical parametric oscillator is 39 mW. When the pump power is 30 mW, quadrature squeezing degree measured by balanced homodyne detector is 2.8 dB. Taking account of detection efficiency, the actual squeezing degree of the output light field of optical parametric oscillator reaches 4.4 dB.