99.9% of SCI journals in the world are in English (only one or two non-English journals are SCI, which should be from Germany and Russia)! Therefore, it must be written in English. But as long as you write Chinese, you can ask a professional company to translate and polish it, which is very convenient. But you must choose a very reliable and formal company. Medical science is the best in China, followed by Wenli and so on. Most of what we see in the market are fake companies.