Theconceptofthenon -arithmeticsequencegreysystemisadducedinthispaper ,accom plishingaprolongationintimeorderrequirement ,discussingthemodelingmethodandequationofthenon -arithmeticsequencegreymodelprovidingatoolfordescribingthenon -arithmeticsequencegreyprocessorsolvingsomeengineeringproblems.

The error analysis by the Time-data -Separation Approach of unequal interval sequence is difficult.

The Time\|data\|separation approach is put forward to solve the prediction problem of unequal interval sequence in Grey theory on the basis of the concept of the class sequence, which keeps the time sequence separate from the data sequence, and then combines the time sequence and the data sequence with the class sequence for constituting model , finally synchronously makes prediction.

This paper apply the gray system theories,regard unit cost of historyical similar item construction as the basis,establish the non-isometric time sequence GM(1,1) model of item construction unit cost.

Based on the relation between the starting-point annihilating images and initial images of unequal time interval sequence,this paper adopted several improved methods to calculate the generalized grey absolute relational grade and generalized grey relative relational grade,which can largely simplify the calculation.