Abstract: Valuation of movement probability has remained difficult to solve up to now without appropriate solution given to it. Today the movement probability used in ore-drawing simulation is still with traditional valuation all through, but it is unadaptable to mining simulations nowadays. So, after the SLS ore-drawing tests carried out for many times, a discussion was made on the movement probability problem and some views were put forward, i.e. assigning different values to k during ore-drawing simulation so as to get different recovery indices. The different ore loosennesses are thus reflected to enable the simulation results to be closer to actual condition and at the same time, to simplify the valuation process of the nine-block probability.