查看apache的日志：
cat /etc/httpd/logs/error_log
发现有大量的内存错误：
[Thu May 06 20:57:06.725839 2021] [:error] [pid 1465] [client 192.168.18.70:55624] PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 7592 bytes) in /usr/share/zabbix/include/classes/graphdraw/CLineGraphDraw.php on line 2555, referer: http://192.168.66.247/zabbix/charts.php?fullscreen=0&groupid=0&hostid=0&graphid=1054
修改php的内存上限和zabbix的php内存上限
vi /etc/php.ini
memory_limit = 1024M
vi /etc/httpd/conf.d/zabbix.conf
php_value memory_limit 1024M
两个地方都修改，重启服务器就好了