采用数值计算方法，研究了初始处于双模SU(1,1)相干态的双模腔场与一个Ξ型三能级原子共振相互作用的光场非经典特性，讨论了初始光场强度、耦合系数和原子态的选择性测量对光场和压缩、光子亚泊松（Poission）分布、模间相干性以及柯西施瓦茨(Cauchy-Schwarz)不等式的影响。结果表明，b模总是呈现和压缩，初始光场强度增强或直接对原子进行态选择测量，b模的和压缩明显地增强；当初始光场强度较弱且直接对原子进行态选择测量，两个模的光子都呈现亚泊松分布；光场两模间总是呈现正相关，而且是非经典关联；柯西施瓦茨不等式不成立。

Nonclassical properties of a two-mode field initially in a SU(1,1) coherent state resonantly interacting with a Ξ-type three-level atom are investigated numerically. The influences of the initial intensity of the light field, the coupling constant and the selective atomic measurement on the sum squeezing of the light field, the sub-Poisson distribution of photon, the mode-correlation properties and the Cauchy-Schwarz inequality are discussed. The results indicate when the initial intensity of the light field is increased or the direct state-selective measurement is performed on the atom, the sum squeezing of mode b is distinctly enhanced, and mode b always exhibits the sum squeezing. When the initial intensity of the light field is small and the direct state-selective measurement is performed on the atom, the two modes always exhibit the sub-Poisson distribution. The correlation of the two-mode light is both positive and non classical, and the Cauchy-Schwarz inequality is violated.