已经把公式中其他内容带入数值，运行不出结果，而且单独计算里面的积分也运行不出来
DSolve[P[\[Omega]] == \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(0\), \(Pi/2 -
10^\((\(-3\))\)\)]\(\((\(-\((\((66416.66137691677`\ \
\((\(-3.655
13834444935
44`*^14\) +
\*SuperscriptBox[\(E\), \(38.683223086147535`\
\*SqrtBox[\(0.7514187629` +
0.005167396856733549`\ Cos[\[Theta]]\)]\)])\)\ \
\((\(-2\)\ \((
\*FractionBox[\(9\), \(1600\)] +
\*FractionBox[\(5.618`*^21\),
SuperscriptBox[\(\[Omega]\), \(2\)]])\)\
\*SuperscriptBox[\(Cos[\[Theta]]\), \(2\)] +
3.0056750516`\ Cos[
2\ \[Theta]])\))\)/\((\((1.280078298226224`*^14 +
\*SuperscriptBox[\(E\), \(19.341611543073768`\ \((
\*FractionBox[\(3\), \(40\)] + 2\
\*SqrtBox[\(0.7514187629` +
0.005167396856733549`\ Cos[\[Theta]]\)])\)\)])\)\ \
\((1.4231221879460945`*^-8 -
\*FractionBox[\(1.2336251290000003`*^-15\ \((10000000 +
\*FractionBox[\(200000\), \(3\)]\ \[Pi]\ Cos[\[Theta]])\)\),
SqrtBox[\(0.62805625` +
1.2336251290000003`*^-15\ \((100000000000000 +
\*FractionBox[\(4000000000000\), \(3\)]\ \[Pi]\ Cos[\[Theta]])\)\)]])\
\))\))\)\))\) \[DifferentialD]\[Theta]\)\), P[\[Omega]], \[Omega]]

……你那个积分有没有符号解都是问题。如果只是需要数值解，那么把Integrate改NIntegrate然后用Table适当算些点出来再用Interpolation之类的函数插值应该是最简单的。