Far-infrared (FIR) reflectance spectroscopy has been employed to study the optical properties for a series of bulk CdZnxTe1-x and CdSexTe1-x wafers. The zone-centre optical phonons for the ternary alloys show a variety of behavior patterns: they exhibit a "one-mode", "two-mode" or "intermediate-mode" behavior depending on the vibration characteristics of the end binary members. The CdSeTe called CST were found to be single-crystal with the zincblende structure. These four samples labeled with CST5, CST15, CST25, and CST35, which correspond with the composition of Se, 5%, 15%, 25%, 35%, respectively. The intensity of CdTe-like TO band decays with x increasing, and the peak position increases from 140 cm-1 to 145 cm-1. In the other hand, the intensity of CdSe-like TO band grows with x increasing, and the peak position of CdSe-like TO band increases from 174 cm-1 to 181 cm-1. We use the model of dielectric function and using Least-Square fit to find the optical and transport parameters. By the infrared spectra analysis, we found the conductivity of CdZnxTe1-x increase with increasing of x value and the conductivity of CdSe xTe1-x decrease with increasing of x value.