This study was purposed to produce blood typing reagents for classifing Cheju horse's blood group factors. The blood typing reagents were prepared by immunization of sixteen pairs out of fourty eight heads of Cheju horses, and seventeen different blood typing reagents (anti-$A_1$, A', H, Z, $ZZ_2$, C, J, K, $P_1$, Q, R, S, $T_1$, $N_1$, $U_2$, X and $E_2$) were prepared from equine isoimmunization. The result for the reagent production and the variation of agglutinin and hemolysin titer are as follows: 1. Anti-K, R, S, $N_1$, $U_2$ and X acted exclusively as hemolysins whereas anti-J, $P_1$, $T_1$ and $E_2$ acted exclusively as agglutinins, however, Anti-$A_1$, A', H, Z, $ZZ_2$, C and Q reacted both as hemolysins and agglutinins. 2. Among the antibodies in most of the reagents reacted both as hemolysins and agglutinins, But anti-$A_1$, H, Z, $ZZ_2$ and Q elevated higher agglutin titers than hemolysin titers, Anti-A' and anti-C elevated higher hemolysin titers than agglutinin titers. 3. Complex antibody $A_1U_2$ was adsorbed $U_2$ and unified to $A_1$, while complex antibody X $N_1$ went through an adsorption process and produced simple antibody X and $N_1$, respectively. 4. In the hemolytic reaction, anti-K and anti-R showed the highest titer, In the agglutination reaction, anti-Z and anti-$ZZ_2$ showed the highest titer. 5. In the case of No.138~No.140 horse immunization combination and No.133~No.146 horse immunization combination, Although production of complex antibody $CE_2$ and $JP_1$ were expected, only anti-$E_2$ and anti-J were produced respectively. 6. The degree of elevation of antibody titer was varied by the blood types and by the types of donor and recipient combination. The fast elevating types, slow elevating types and types that never elevate the antibody titer were identified.