The discussion of St. Brigid's cross as a complex symbol intends to illustrate the rich cultural implication of St. Brigid's Cross. Beginning with St. Brigid and St. Brigid's Day, the essay firstly introduces the importance of this day. Then it continues to demonstrate the strictly regulated process of making one proper St. Brigid's cross, with some variations included. The straw, the main material to make crosses, has the implication of securing fertility, which is also noted in the essay. Types of cross are generally introduced with pictures for reference. At last, the cross's cultural implications -to protect and to ensure fertility are addressed in detail.