R language has been the most popular computing language in scientific research, but its application in agricultural experiment data analysis in China is still very limited. We are writing two articles to introduce R language and basic application in the agricultural experiment data analysis. As the first article, we are focusing on some very basic knowledge for the new beginners, such as R software download, install, how to enter data and do some basic computations and make simple graphs. We hope this article will help agricultural scientists in China gain some preliminary understanding of R language and try using R to analyze trial data.