I am a project leader in the Software Development Department.  =  good sentence

I am a project leader of the Software Development Department

I have been working here for the past five years. =  good sentence

My main role as leader is to schedule of development and issue management.

My main role as a leader are schedule of development and issue management.

Recently the project is developing mobile security solutions.= good sentence

In that project to design and implement and testing has a variety of experiences.

In that project I do designing, implementing and testing which would require a variety of experience.

I'm proud to be involve in the very meaningful project.

I'm proud to be involve in a very meaningful project.

I hope my hard work will help the company. I really enjoy my job. = good sentence

Hey Mickey!

Some revisions on the sentences you made are written just below the sentence you made. The correction is in blue so please take note of the structure of the sentence and a missing  article or preposition that should be in your sentence.

Good night!