The present study was conducted to measure the cardiorespiratory endurance of Jeju crossbred horses according to hill tests and exercise intensity, thereby providing foundational data for evaluation of running capability of horses. The nine Jeju crossbred horses were subjected to the hill test with an inclination of around $30^{circ}$ and six out of nine horses were used to measure the cardiorespiratory endurance according to three different exercise intensities (moderate, heavy, and very heavy). The running time for the hill test was 205 sec on average, while high deviation was observed between horses from 167 to 258 sec. In addition, the running time for the hill test was highly correlated with moderate exercise. While no significant difference in average heart rate was found between exercise intensities, a trend of large variation was found in the average heart rate between horses. The heart rate recovery was highly correlated with heavy exercise and very heavy exercise. The results showed that no significant difference in average heart rate was found among three exercise intensities, but there are large individual variations among horses.