The normalized modefield and power proportion inside the core are also studied under different structure parameters of triangular segmented core with step ring optical fiber by this method 用此方法研究了帶階躍環的三角型分段折射率分布光纖中歸一化模場半徑與芯層傳輸功率及總傳輸功率比值隨光纖不同結構參數的變化規律。