Objective Synchronization signal has two output types in the acquisition of the image data by functional magnetic resonance imaging (fMRI). One type is that a synchronization signal is outputted after acquiring each layer image. The other type is that a synchronization signal is outputted after acquiring a whole brain map. However, for the first type of synchronization signal, there is a loss of synchronization because the synchronization signal is too dense to be recorded in time by the stimuli-controlled computer. Therefore, in this paper a single parameter (synchronous parameter) synchronizer is designed based on CPLD. Methods The synchronizer counts the positive edge of the first type of synchronization signal in the acquisition of a brain map. Meanwhile, the output of the synchronizer remains high level and will not be pulled down to low level during the counting period until the last synchronization signal is coming. The synchronizer achieves the translation of the synchronous signal from the first type into the second type. Then we simulate the signal conversion by Quartus 9.1 to verify its functionality. Results The first synchronization signal is processed into the second synchronization signal through the CPLD processor. In addition, the synchronizer based on this design is also successfully applied to GE Sigma 3.0T. Conclusions This research designs a synchronizer which has conversion capability for synchronization signals and successfully achieves the transformation output type. The synchronizer reaches the synchronization requirements with better compatibility.