输入任务包平均价格、聚类中心位置，任务包内会员的指标。    这句话太长，想让他分为两行，如下：

               输入任务包平均价格、聚类中心位置，

                任务包内会员的指标。

\documentclass[UTF8,a4paper]{ctexart}

\usepackage{graphicx}

\usepackage{tikz}

\usetikzlibrary{shapes.geometric, arrows}

\begin{document}

\begin{figure}[h]

\centering

\thispagestyle{empty}

% 流程图定义基本形状

\tikzstyle{startstop} = [rectangle, rounded corners, minimum width = 2cm, minimum height=1cm,text centered, draw = black, fill = red!40]

\tikzstyle{io} = [trapezium, trapezium left angle=70, trapezium right angle=110, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill = blue!40]

\tikzstyle{process} = [rectangle, minimum width=3cm, minimum height=1cm, text centered, draw=black, fill = yellow!50]

\tikzstyle{decision} = [diamond, aspect = 3, text centered, draw=black, fill = green!30]

\tikzstyle{point}=[coordinate] 

% 箭头形式

\tikzstyle{arrow} = [->,>=stealth]

\begin{tikzpicture}[node distance=1.5cm]

%定义流程图具体形状

\node (start)[startstop]

{开始};

\node (in1) [io, below of = start]

{输入任务包平均价格、聚类中心位置，任务包内会员的指标};

\node (pro1) [process,below of = in1]

{计算任务包的价格、距离、会员能力指标};

\node (pro2) [process, below of = pro1]

{应用多元 logistics 回归分析建立任务包完成度模型};

\node (in2) [io, below of=pro2]

{ 输出每个任务包的完成度   };

\node (stop) [startstop, below of=in2]

{结束};

%连接具体形状

\draw [arrow]   (start)  -- (in1);

\draw [arrow] (in1) -- (pro1);

\draw [arrow] (pro1) -- (pro2);

\draw [arrow] (pro2) -- (in2);

\draw [arrow] (in2) --  (stop) ;

[->,>=stealth]\end{tikzpicture}

\caption{任务包完成度的建立与求解过程}

\end{figure}

\end{{document}}