Based on the empirical electron theory of solids and molecules (EET), the statistical values of valence electron structure parameters of Al-5Zr master alloy melt were calculated, and the crystallization process models of the Al3Zr phase in the Al-5Zr melt were built at high and low pouring temperatures. The effect of pouring temperature on the morphology, size and the amount of primary Al3Zr phase during the solidification of Al-5Zr master alloys was investigated. The results show that the morphologies change from small blocks to long needles, the average size increases and the amount decreases for the Al3Zr crystals with the increase of pouring temperature. When the pouring temperature is below 1000 °C, the Al-Zr and Zr-Zr clusters with larger quantities and larger gather, nucleate and finally form a large number of small blocky Al3Zr crystals; when the pouring temperature is above 1000 °C, the Zr-Zr clusters with fewer quantities and largeraggregate, nucleate and ultimately form a small number of Al3Zr crystals with long needle shape. The established models agree well with the experimental results