You may not be able to stop inappropriate laughing on your own, and that’s okay! A therapist can help you identify what’s causing your laughter and recommend better ways to overcome it.  You can find a therapist by searching online. People may experience periodic bouts of inappropriate, uncontrollable laughter due to conditions like pseudobulbar affect (PBA), bipolar disorder, dementia, stroke, or other neurological conditions. Selective serotonin reuptake inhibitors (SSRIs) can help some people find relief from recurring bouts of laughter. Your doctor will determine if medication is right for you. SSRIs do not help all patients, and they could interfere with other medications. Both of these conditions can cause you to laugh inappropriately. With Tourette Syndrome, you may experience the laughter as a tic, while Obsessive Compulsive Disorder (OCD) may cause you to laugh out of habit. Fortunately, you can learn to overcome these behaviors, though it is difficult. Cognitive-behavioral therapy can help you learn to recognize when you may laugh and learn to control it.

TL;DR in Chinese:
如果你的笑是某些潜藏的问题引起的，你要和医生谈谈。 问问医生，你是否可以使用选择性血清素再吸收抑制剂（SSRIs）。 如果你有妥瑞氏症或者强迫症，最好接受认知行为治疗。