Mixing conditions such as addition sequence of zinc oxide powder, an activator to accelerate vulcanization, and temperature and time of carbon black mixing stage have been changed to measure both of scorch time and cure rate of the green compound and to find optimum mixing condition producing a green compound that would proceed successfully without any scorch during calendering and extrusion steps, etc. Since the green compound prepared from adding zinc oxide in the first stage with mixing at 363 K for 4 minutes and also treated further in sulfur mixing second stage at 333K for 2 minutes has lengthened the scorch time 10% more and has showed the same cure rate as the others mixed at higher temperature for longer period in the first stage, it is concluded that the above mixing conditions may save the cost of preparing green compound and its premature vulcanization preserving the quality of the product, as mechanical properties of the cured rubber measured by universal test machine had exhibited.