Using 0.1 TW, 100ps pulse-width high-power laser to irradiate the surface of plane aluminium targets with different polarizations (P-polarization or S-polarization), the LPX spectral line of aluminium ions was photographed by a X-ray crystal spectrometer. The relation between electron temperature of laser plasma and the incident angles of the laser beam was obtained. It shows that there is resonant absorption in the plasma when the laser power density is in the order of 1015W/cm2. The Ka spectral line emitted by the aluminium target originates mainly from fast electrons in our experimental conditions.