Fast spin echo is widely used for ASL acquisition. However, if the flip angle reduced to minimize SAR and/or stabilize signal evolution over the echo train, the fluctuation of CSF increases markedly. This work explored the influence of minimum flip angle, and crusher strength in ASL acquisition. A CSF-prioritized background suppression (BS) planning was also performed. We found that increasing minimum flip angle together with reducing crusher in superior-inferior direction benefits the stability of ASL acquisitions. Prioritizing CSF suppression in BS was also helpful.