The farmland crop information is the important foundation of developing fine agricultural practice. Crop information acquisition technologies have become the most effective means to increasing crop production and improving crop quality. In this paper, on the basis of introducing the characteristics of farmland crop data, different farmland crop information acquisition methods are surveyed in detail, sections need to be improved of these methods and related core technologies will be discussed. At last, this paper gives a table about crop information acquisition technology and sensing instrument systems applied in different levels (individual level, area level and wide-area level).