首先，安装OpenMP

sudo apt-get install libomp-dev

然后，编辑Clion生成的CMakeLists.txt，在任意set后面加上下面的代码

find_package(OpenMP)
if (OPENMP_FOUND)
    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
    set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
endif()

下面是一个完整的例子

cmake_minimum_required(VERSION 3.13)
project(test C)

set(CMAKE_C_STANDARD 99)
find_package(OpenMP)
if (OPENMP_FOUND)
    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
    set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
endif()
add_executable(test main.c)

然后，我们编写一个测试程序

#include <stdio.h>
int main(){
#pragma omp parallel for
    for(int i=0;i<10;i++){
        printf("%i\n",i);
    }
    return 0;
}

运行后，应该可以看到乱序输出的数字，代表OpenMP运行成功