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Silicon wafer slicing manufacturing process exhibits several characteristics. They are: (1) the product type is small batch production, (2) saw cutting must be very precise, (3) the process run time is long, and (4) inspecting samples is difficult. Furthermore, the process involves several synchronously occurred multiple quality characteristics, such as thickness (THK), bow and warp, which must be closely monitored and controlled. Synchronously monitoring multiple quality characteristics is more expensive than monitoring a single quality characteristic in the manufacturing process. The sizes of inspected samples in the existing process are difficult to maintain the quality control chart. Grey situation decision method is used to screen the worst quality control chart. Grey situation decision method is used to screen the worst quality characteristic from the synchronously occurred multiple quality characteristics to monitor the process. Finally, a case study is presented to demonstrate the feasibility and effectiveness of proposed decision method. The exponential weighted moving average (EWMA) control chart is used to verify that the process quality is more reliable.