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Objective:To investigate the parameters optimization of different fetal MRI brain scan in different fetal age. Object and Methods : Collecting the cases of pregnant women who are more than 24 weeks pregnant in our hospital,and Ultrasound screening suspected abnormal fetal brain development, need to do MRI examination of the fetal brain targeted. Using PHILIPS Achive 1.5 T double gradient magnetic resonance imaging equipment, phased array large SENSE XL torso 16-channel coil, advanced, supine or lateral position, based on principles of patient comfort. Sccanning sequence:(1) Single-shot fast spin echo(SS-TSE);(2)Others: Balanced steady state free precession(B-TFE);T1 high resolution isotropic volume excitation(THRIVE);DWI and Single-shot sequences for water imaging. Case groups: (1) 24 ~ 28 gestational weeks; (2) 28 ~ 32 gestational weeks; (3) > 32 gestational weeks. Adjustable Parameters are: TE, TR, length of ETL, acquisition bandwidth, NSA, Flip angle, collection model, matrix, Slice thickness and Slice spacing. Results: 50 cases of fetal MRI brain examination: the expansion of the lateral ventricle (23), posterior cranial fossa abnormalities(11), lateral ventricle cyst (3), normal(13).The results according to the parameter adjustment of different gestational age groups: Increase the TE time can improve the T2 contrast, which can optimize the structure display of the brain especially the edge. Adjust the collection bandwidth and the ETL can affect the ES time , which can reduce image artifacts. We can chose the M2D acquisition mode, which can reduce the interference between the layers, meanwhile can obtain good images without the pregnant women breach to cooperate. In consideration of the SAR values influence on patients , reducing the flip angle is a good choice. Besides, matrix, slice thickness and gap should be adjusted according to the fetal gestational age and the tolerance of the pregnant women. Conclusion: SS - TSE sequence of scanning speed, and get the similar T2WI images, can be use as a basic sequence for fetal craniocerebral examination. In clinical application, the scanning parameters should be aimed at different gestational age adjustment, made to optimize image quality.