Why my keyword ranking drop recently?

dropped after how long?

I am aware of some recent changes over at google. You could do worse than visit this article which concentrates on recent Google changes.

https://moz.com/google-algorithm-change

Good luck

Hi Chenbui,

You are very correct in your analysis. It is not true that the keyword ranking has dropped recently, but google has improved their search strategy. Two years back google was bit concentrating and giving some importance to the keywords that people are using in their website but now their only concern is the peoples interaction (like the amount of time spend on reading the contents in the website, number of page visits, comments posted, number of post shares in social media, etc) and this can be achieved only by improving the quality of the website. Let me explain you by giving some examples.

Consider a person is typing in google on "How to reduce belly fat in 30days"

By this we can understand that this person is trying to find some valuable tips to reduce weight. As i mentioned before 2 yrs ago google was giving bit importance for the usage of keywords, so there were many website which really has been concentrating on keywords just to rank them high on google, forgetting about the quality of the content, some times you could see website with the same search name example: www(dot)howtoreducebellyfatin30days(dot)com 90% of these websites according to my knowledge will have very less quality . So websites like these were also ranking up.

So inorder to avoid this google has reduced giving importance to keywords (not neglecting completely) and increased their concentration on the quality of the content.

Thanks,
Anand.

We rank keywords using the power of backlinks. I think almost all the writer try to maintain on page SEO when they write a content.
So Off Page SEO is the factor that varies from man to man. If someone can do better than you using the same keywords, he/she will rank better than you.
You should know, the validity of your backlinks only six months. So always try to create backlinks and re-publish your posts after editing.