why when i lose ranked game i lose more lp !!?

It means your performance in individual games is overall below average for your current elo. So the system is trying to correct you to the proper elo.

To expand upon poster above me:

You have a hidden rating called mmr which is independent of your visible rank. I'm not sure if it's on a curve (which I think is the case) or if it's a predefined value by the devs, but if your mmr is below what "belongs" in a certain division then your LP gains are throttled until you win more games and bring your mmr score up to par. It's basically a system to curb instances of people climbing beyond where they belong due to pure luck (i.e. getting carried repeatedly).

Maybe it's more accurate to say that hidden MMR is your "true" rank while gold, silver, ect are just placeholders to give you an easily digestible idea of where you are. As long as you maintain a positive win rate your mmr will rise and soon enough you'll be getting normal LP gains