cause着重指产生或造成某事发生的原因,往往指造成不好的影响，reason着重指解释或说明某事发生的理由或原因。cause用于表示具有明显因果关系的原因。reason有时能与cause换用，但上下文必须有能够查得出的或可以解释得出的因果关系。

1、cause指导致某事发生的行为、事件等。

2、reason指某事发生的原因或做某事的正当理由，常后接介词 for 及 why 或 that 引导的从句，作“理由”解时还可后接动词不定式。

例句：Lack of physical exercise is the leading cause of obesity in young students.

例句：She gave her reason for being late.

cause更多地指“原因、起因、根源”，即造成一种事实或现象的比较直接的、根本的客观条件、情况、事件、力量等;

reason更多地从理性的角度出发，强调“推理”,指对于某个情况或看法从逻辑推理上引出结论的“理由”。

例句：The police were still confused about the cause of this traffic accident.

例句：I have no reason to change my mind on this matter.

cause既可以作名词又可以作动词

1、原因;起因(n.)

例句: What’s the cause of the forest fire last night?

2、理由;动机;缘故(n.)

例句: I think there is no cause for your complaining.

3、(支持或为之奋斗的)事业，目标，思想(n.)

例句: He has been fighting for this good cause for his whole life.

4、使发生;造成;引起;导致(v.)

例句: The poor harvest last year was caused by bad weather.

reason的用法

1、原因;理由;解释(n.)

例句:He resigned for the simple reason that he was not well paid.

2、思考力;理解力;理性(n.)

例句:The woman lost her reason after her son’s death.

3、道理;情理;明智(n.)

例句:Don’t push him! He is not open to reason at this moment.

4、推理;推论;推断(v.)

例句:Sue reasoned that one of her classmates had stolen her purse on the PE class.