This study analyzed the casula wearing by Catholic priests. By understanding various applications of the priests' wearing of casula, we can understand the meaning of wearing casula, situational judgment, and the role and status of priests. Ultimately, the Catholic symbol and meaning of the casula can be found. The purpose of this study is to examine the basic setting of the casula, the setting according to the status of the priest, and the origin of the casula. Second, this study to understand the design of the pattern shown in the casula. The patterns containing the symbol and the liturgical period were examined, and the method of making the pattern design was considered. Third, various symbols appearing in examples of priests' rituals were considered and analyzed. The method of this study was to utilize various pictures acquired during interviews with priests and nuns and to perform content verification. As a result of this study, the aspects of form, color, and pattern were shown through the wearing of casula during various situations. First, the morphological symbols appearing in the rituals are the simplified casula that hangs on the stola on the top of the alb and the symbols of the form according to the priest's status. In the liturgy, the casula is put on the outermost side as for basic wearing, but in the case of celebration or the attendance at celebrations other than the liturgy, it is the same as simplified wearing. Second, in terms of the symbol and color, the basic colored casulas were worn to match the time and character of the liturgy, and in addition, on the priests' ordination ceremony and celebration day the priests wore white casulas. Third, the symbol of the pattern used in the casula was a Cathoric pattern according to the period in the basic casula wearing of the liturgy. In addition, the patterns were produced by combining the patterns and meaning of the priests that were used in the casulas of the priests' ordination ceremony. The design of the pattern used in the beatification mass casula and the Mass of Peace casula during the Pope's visit to Korea in 2014 used the same motif as the Pope's design, but the simplified pattern was produced for the casula of the Cardinal and bishops. Through this, it is possible to understand the situation where a morphological symbol appears due to a distinction according to the role and status of the priest. This shows that the symbols that appear are the cross and should also consider the complexly, shape, color, and pattern.