#include<stdio.h>   
struct Staff{
        char  name[20];
        double num;
    };
int main()
{
    int i,j, p=0;
    double key;
    struct Staff temp;
struct Staff staff[10]={{"郑 兵",201003020076},
                        {"宋 琪",20100302001},
                        {"宋 健",201003020077},
                        {"丹 丹",201003020054},
                        {"马 文",201003020090},
                        {"孙 林",201003020017},
                        {"王 昆",201003020012},
                        {"段 鹏",201003020040},
                        {"小 六",201003020080},
                        {"李 勇",201003020069}};     
    for(i=0;i<10;i++)
        printf("%s %.0lf\n",staff[i].name,staff[i].num);
        for(j=0;j<10;j++)
            for(i=0;i<9-j;i++)
                if(staff[i].num>staff[i+1].num){
                    temp=staff[i];
                staff[i]=staff[i+1];
                staff[i+1]=temp;
                }
                for(i=0;i<10;i++)
                    printf("从小到大输出:%s %.0lf\n",staff[i].name,staff[i].num);

                while(p==0){
                    printf("input a staff's number:\n");//查询
                    scanf("%f",&key);
                    for(i=0;i<10;i++)
                    if(key==staff[i].num)
                    {
                        printf("%s %.0lf\n",staff[i].name,staff[i].num);
                        p=1;   
                    }
                    else{
                    
                        }
                    if(p==0)
                        printf("输入有误，重新出入！\n");
                }
                        return 0;      
}

#include<stdio.h>   
struct Staff{
        char  name[20];
        double num;
    };
int main()
{
    int i,j, p=0;
    double key;
    struct Staff temp;
struct Staff staff[10]={{"郑 兵",201003020076},
                        {"宋 琪",20100302001},
                        {"宋 健",201003020077},
                        {"丹 丹",201003020054},
                        {"马 文",201003020090},
                        {"孙 林",201003020017},
                        {"王 昆",201003020012},
                        {"段 鹏",201003020040},
                        {"小 六",201003020080},
                        {"李 勇",201003020069}};     
    for(i=0;i<10;i++)
        printf("%s %.0lf\n",staff[i].name,staff[i].num);
        for(j=0;j<10;j++)
            for(i=0;i<9-j;i++)
                if(staff[i].num>staff[i+1].num)
                {
                    temp=staff[i];
                staff[i]=staff[i+1];
                staff[i+1]=temp;
                }
                for(i=0;i<10;i++)
                    printf("从小到大输出:%s %.0lf\n",staff[i].name,staff[i].num);

                while(p==0)
                {
                    printf("input a staff's number:\n");//查询
                    scanf("%lf",&key);
                    for(i=0;i<10;i++)
                    if(key==staff[i].num)
                    {
                        printf("%s %.0lf\n",staff[i].name,staff[i].num);//此处输出应是lf格式
                        p=1;   
                    }
                    else{
                    
                        }
                    if(p==0)
                        printf("输入有误，重新出入！\n");
                }
                        return 0;      
}

这个我也不知道。。。。

为啥在scanf中输入f时，不能查询呀？float允许的最大值不也是15位嘛？

因为你前面在定义key时定义的是double格式啊。