my website Alxa rank into my own country is 24000 and my competitor website is 34. me and my competitor both translate the foreign post. i really don't know what kind of post should i have to translate. is it good to translate my competitor post again( i mean about a translation that is completely different(word and verb)). does it improve my Alexa rank?
First of all, Alexa rank is more about traffic than your content. More traffic = higher rank.
From an SEO standpoint, copying another sites content is never a good idea. Even if you 'spin' the article like you mentioned by changing around certain words or re-ordering things Google will often pick up on this as 'duplicate content' and it will negatively impact your SERPS.
I would focus on increasing your website traffic if you really care about increasing Alexa rank, though I have always thought of Alexa rank as pretty meaningless. Create good, unique content and the traffic will come - worry less about copying your competitor and more about creating original content :)