I don't understand why you are applying in English to a German university. Is that the normal thing to do?

Is a superior knowledge of English a requirement for this degree program? Do you think perhaps it might be wise to let them see the actual level of your English knowledge?

To the people who concern，No. Dear Sir/Madam, or say 'Dear Mr. Smih if you know the person's name.

Start  by saying briefly what you are applying for. They probably get a lot of motivation letters every day.

I think you should start right away with your personal views, and try to avoid too many purely general comments.
   Thank you for your attention to these materials. Chemical and process engineering is a fast growing field with an increasing number of applications deeply influencing our lives in today's world, and also a subject with easy expandability and tremendous potential. Those are very attractive to me and make me decide to follow my career in. Germany is famous for rigour, meticulosity, inspiration and innovation, which I believe are the most important factors of science, and are the goals I keep pursuing. The precise scientific spirit and strict education system, as the foundation of not only Germany’s world-top science and technology but also world-class research and excellent teaching performance, make me yearn for.

I feel you have included too many unimportant details here. Focus on the important things.

My undergraduate performance was particularly strong in mathematics, physics and chemistry, with all A in mathematics courses and mostly A in physics and chemistry courses. I have got ABC Scholarship in 200X and ABCD Scholarship  in 200X. I did two internships in my third year of undergraduate study, which are to participate in the whole production process of P.V.A in ABCDE co., Ltd, and brewing process in ABCDEF co., Ltd. As the student who is eager for the advanced knowledge, I worked in the lab under the dean on the research project about fermentation during last summer vacation, and I learned how to use the apparatus like SEM, X-ray powder diffractometer and zeta potential analysis instrument in the research on the interaction behavior between biomolecules and magnetic nanoparticles. Now I am well prepared for the further challenging study and research, and I wish that I can continue them in the faculty of ABC in the University ABC. I believe that through your master program I will gain thorough education and excellent research experience. Make a separate paragraph for your future plans. After the master program, I would like to continue the doctoral study if it is possible or I would like to find a job in a transnational corporation in ABCD.

Add a concluding paragraph.

Sincerely,

Clive