In this paper, we discuss about how monetary policy affects the relationship between inflation and unemployment from the perspective of New Monetarist Economics. We use a monetary search model base on microeconomic theory to discuss the influence of government purchases of intermediate goods. I find that government purchases have crowding-out effect that final goods firms reduce purchasing intermediate goods. In addition, intermediate goods firms increase their layoff because of decreasing transactions. We will get higher unemployment rate and therefore a positive Phillips curve in long run.