A　new　way　that　is　thermal　assisted　high-pressure　water　jet　ultra　fine　comminuting　has　been　used　to　comminute　the　minerals　on　the　experiments.　The　mineral　particles　were　damaged　by　thermal　shock　before　they　were　comminuted　finally　by　high　pressure　water　jet.　The　experimental　results　on　the　ultra　fine　comminuting　coal,　kaolin　powder　show　that　the　good　comminution　effect　can　be　gotten　making　use　of　the　method.　When　the　pressure　increases　to　a　certain　value,　the　high　comminuting　efficiency　can　be　gotten　at　the　first　comminution.　The　particle　size　distribution　of　products　by　water　jet　comminuting　heat-treated　minerals　is　narrower　and　the　particle　size　is　more　uniformity　than　untreated.　At　the　same　time,　the　working　pressure　of　water　jet　can　be　reduced　lower　for　the　heat　treated　minerals　if　the　same　particle　size　distribution　is　gotten.