The characteristics of martensitic transformation and magnetostructural coupling have been investigated for MnNiGe1−x Gax (x=0-0.30) alloys. It has been found that the martensitic transformation temperature of the system can be deceased about 400 K by doping a low content of Ga to substitute for Ge. Adding Ga may weaken the hybridization and at the same time enhance the magnetic exchange interaction, which are responsible for the increase of the atomic moment and the Curie temperature in the austenitic phase. The structural and magnetic phase diagram was obtained to show some important points: 1) the decreased transition temperature successively pass through the Neel temperature and the Curie temperature; 2) the Curie temperature window still opens during the doping; 3) the magnetism can effectively affect the transformation behavior. The metamagnetization and the preparation influence on the transformation are also observed. These properties are significantly beneficial to the development of new magnetostructural materials.%研究了MnNiGe1−x Gax (x=0-0.30)系列合金中成分、结构、马氏体相变性质和磁性的相互关系.在较小的成分范围内， Ga取代Ge元素可有效地将马氏体相变温度降低近400 K. Ga的引入削弱了体系中的共价成键作用，马氏体相显示出磁交换作用的增强.相图显示，掺杂使马氏体相变先后穿过TN和TC两个磁有序温度，居里温度窗口效应在体系有存在的可能，磁性对相变温度的成分关系有所影响.实验观察到合金变磁转变的特性及相变行为对制备方法的敏感性.这些特性的发现，有利于进一步优化这类材料的磁结构和相变特性，获得具有应用价值的新材料.
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