To　solve　the　long-time　consuming　and　wasting　in　measurement　of　the　static　evaporation　rate　of　welded　cryogenic　insulated　high　vacuum　gas　cylinders,　the　evaporation　rates　of　liquid　nitrogen　in　the　cylinders　were　measured　in　the　lab　by　weighting.　Grey　model　GM(1,1)　is　used　to　predict　the　evaporation　rates　based　on　the　measuring　data.　The　studies　show　that　evaporation　quality　within　72　hours　can　be　predicted　based　on　the　data　tested　within　60　hours　by　GM(1,1)　model.　The　relative　error　of　evaporation　rates　between　prediction　value　and　measured　value　is　less　than　5%.　By　applying　this　prediction　method　in　the　automatic　measuring　system　of　evaporation　rate,　the　testing　efficiency　of　the　insulated　cylinders　is　improved,　the　turning　over　rate　of　the　cylinders　is　increased　and　the　cryogenic　liquid　consumption　in　the　inspection　is　lowered.