The electrical and magnetic properties of pervoskite structures have great scientific interest. In this report we present a spectroscopy study of LaCa0.7Mn0.3O3/MgO thin film to determine its optical properties. Terahertz time-domain measurements were performed to obtain THz transmission and emission spectra. The LaCa0.7Mn0.3O3 thin film used in this work was grow on single crystal substrate MgO (100) by pulsed laser deposition (PLD) technique and the transport measurement has shown that the thin is a colossal magnetoresistance (CMR) material. The insulator to metal transition temperature, TIM is about 150K according to the temperature dependence of the resistivity measurement. On the THz transmission measurement, the spectra of the MgO and the thin film were taken in both air and N2 to determine the effect of water absorption. In the emission measurement, the femto-second laser is incident on either the LaCa0.7Mn0.3O3 thin film or on the InAs wafer. The emitted THz signals in both cases were obtained and compared.