which lanagusge is similar to laos langauge ?

The language most similar to Lao is Thai. They are closely related, mutually intelligible to a large extent, and share a lot of vocabulary and grammar.

Other close languages

• Isan : spoken in northeastern Thailand and very close to Lao.
• Shan : also related and shares some sound and structure similarities.
• Tai Lü / other Tai languages : part of the same broader language family, so they can feel similar in form and sound.

Simple answer

If you want the closest everyday match, Thai is the main answer. If you want, I can also give you a ranked list of the top 5 most similar languages to Lao.