Bamboo hardness test standards are not available. This study developed a new test method for bamboo indentation hardness with the U-shaped cylindrical and V-shaped compression heads in bamboo rings with different lengths. The mechanical behaviors of bamboo rings under two kinds of compression heads were analyzed. The results showed that U-shaped indentation hardness and V-shaped indentation hardness were closely correlated with compression strength and that the difference between U-shaped indentation hardness and V-shaped indentation hardness was significant. However, the bamboo rings with different lengths showed no significant difference in indentation hardness.