This　study　tries　to　design　a　task　abort　policy　for　distributed　computing　systems　in　order　to　enhance　its　mission　completion　probability.　Particularly,　a　task　may　need　to　be　aborted　when　it　cannot　be　completed　at　a　time　threshold.　This　study　assumes　that　the　time　of　each　computer　spent　on　executing　its　task　on　follows　Weibull　distribution.　Some　additional　rules　are　introduced　from　the　aspect　of　practical　application.　Based　on　an　approach　of　multi-valued　decision　diagram,　a　system　reliability　is　evaluated　considering　the　abort　policy.　©　2020　IEEE.