In this study, the effect of cone angle of seven-hole probe on the accuracy of measured flow angle and velocity has been investigated. The seven-hole probe consisted of seven 1mm OD stainless inner tubes and one 3mm ID stainless tube. Six cone angles of $45^{circ}$, $60^{circ}$, $75^{circ}$, $90^{circ}$, $105^{circ}$ and $120^{circ}$ were tested. Calibrations of the seven-hole probes were conducted within ${pm}60^{circ}$ range with the interval of $5^{circ}$. Analysis results show that the effect on the cone angle was not significant on the accuracy of the measured flow angle, pressure, and velocity. However, the data reduction method had more effect on the measurement accuracy.