核试验（nuclear test），又称核试爆，是为了军事研究和科学研究目的，对核爆炸装置或核子武器在预定条件下进行实际的爆破试验。不少国家在20世纪均发展出核武并进行试验，有关部门可透过这些试验去了解这些武器如何运作。其主要目的是：鉴定核爆炸装置的威力及其他性能，验证理论计算和结构设计是否合理，为改进核武器设计或定型生产提供依据；在核爆炸环境下研究核爆炸现象学和各种杀伤破坏因素的变化规律；研究核爆炸的和平利用等。它是一项规模很大、需要多学科、多部门协同配合和耗费大量人力、物力的科学试验。然而在历史上大部分的核试验中，多半带有政治上威吓的意味。

Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Throughout the 20th century, most nations that developed nuclear weapons tested them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how personnel, structures, and equipment behave when subjected to nuclear explosions. Nuclear testing has often been used as an indicator of scientific and military strength, and many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status by means of a nuclear test.